Alpinestars Tech KX Short Sleeve Top

From £52.80 Incl. VATFrom £44.00 Excl. VAT

Motorsport equipment for practice and track use rather than homologated competition. Ask us anything before you order: the showroom team use this kit, not just sell it.

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Size/Fitting guide

SKU: 475-0125 Category: Karting Underwear

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The Alpinestars Tech KX Short Sleeve Top is engineered for kart racers who demand the perfect combination of performance, comfort, and freedom of movement. This ultra-lightweight and highly breathable base layer is designed to enhance your driving experience by efficiently managing perspiration and supporting maximum flexibility.

Crafted with advanced moisture-wicking technology, the Tech KX Top helps regulate body temperature by drawing sweat away from your skin, keeping you cool and comfortable even under intense racing conditions. Its seamless, close-fit design eliminates pressure points, ensuring a distraction-free experience so you can stay fully focused on precision and control.

The innovative mesh construction promotes unrestricted movement, giving you the edge needed for quick, responsive handling. Purpose-built for competitive kart racing, the Tech KX Top provides superior breathability and exceptional comfort, helping you perform at your best. Stay cool, move freely, and experience the ultimate in performance-driven design with the Alpinestars Tech KX Top.

Key Features:

Ultra-Lightweight Stretch Mesh: Thin, flexible mesh enhances freedom of movement, improving agility and reducing fatigue during races.
Ergonomic Cut Design: Body-mapped cuts ensure unrestricted movement for precise control and handling.
Jacquard Mesh with Diamond Pattern: Boosts breathability while maintaining a snug, lightweight fit, allowing airflow to regulate body temperature.
Advanced Moisture-Wicking Technology: Effectively pulls sweat away from the skin, keeping you dry during intense racing sessions.
Flat Seams and Welded Hems: Minimises rubbing and chafing by reducing pressure points, delivering superior comfort for extended periods.
Seamless Tubular Torso Construction: Provides a smooth, bulk-free fit for optimal comfort under a race suit.
Enhanced Comfort Fit: Updated design tailored for kart drivers ensures a seamless feel with maximum support.

Sizing:

S – 89/95cm chest
M – 95/100cm chest
L – 100/106cm chest
XL – 106/111cm chest

Additional information

Brand	Alpinestars
Approval	Non-FIA
Colour	Black, White
Size	S, M, L, XL
Product Type	Karting

Karting underwear size guide

Kart underwear is sized on your body, the same chest and waist measurements as a kart suit. The complication is that this category uses four different labelling systems, sometimes within the same brand.

System	Sizes	Which products
Single letters	S, M, L, XL, XXL	OMP Padded Shorts, Alpinestars Tech KX, Sparco B-Rookie
Paired letters	XS-S, M-L, XL-XXL	The OMP KS range, Alpinestars Ride Tech
Wide pairs	S/M, L/XL, XXL/XXXL	OMP KS Winter-R tops and long johns
One size	no choice	All the balaclavas: OMP KS, Sparco Rookie and Softknit, Alpinestars Ride Tech

The quickest routeSize it from your kart suit. The letters follow the same body ladder. If you are a Sparco M kart suit you are a Sparco M top and shorts. If you have not bought the suit yet, measure your chest and waist and use those.

Measure these

AChestAround the fullest part, under the armpits, tape horizontal.

BWaistAround your natural waist, level with the navel.

CShoe sizeOnly needed for socks. They go by foot, not by clothing size.

Charts

SparcoLetters follow their body ladder.▼

Letter	Suit size	Chest (cm)	Waist (cm)
XS	44 / 46	86 – 93	74 – 81
S	48 / 50	94 – 101	82 – 87
M	52 / 54	102 – 109	88 – 97
L	56 / 58	110 – 117	98 – 105
XL	60 / 62	118 – 125	106 – 113
XXL	64 / 66	126 – 133	114 – 121

Sparco publish no separate underwear chart. These are the bands from their own body size chart, which is what their letters follow. The K-Carbon tops run XXS, XS-S, M-L and XL, so the middle two each cover two of these rows.

AlpinestarsXS to XL published, from their tech layer range.▼

Letter	Chest (cm)	Waist (cm)
XS	86 – 90	72 – 76
S	90 – 94	76 – 80
M	94 – 98	80 – 84
L	102 – 106	88 – 92
XL	106 – 110	92 – 96

Their own chart jumps from 98 cm to 102 cm between M and L, so a 98 to 102 cm chest falls in a gap. Ring us if that is you.

OMPSold in letters and pairs with no published measurements.▼

OMP put a size chart on every kart suit, boot and glove product page but not on their underwear. Rather than convert from another brand’s chart, size the KS range from your OMP kart suit size, or send us your chest and waist and we will confirm before it ships.

The KS Winter-R tops and long johns use unusually wide pairs, S/M, L/XL and XXL/XXXL, so each garment covers three suit sizes. If you are on a boundary there, take the larger.

Socks

OMP sell the KS sock in S, M and L against shoe size rather than clothing size.

Size	UK shoe	EU shoe
S	UK 6.5 – 7	EU 40 – 41
M	UK 8 – 9	EU 42 – 43
L	UK 9.5 – 10.5	EU 44 – 45

OMP publish the shoe ranges for their racing socks and the KS kart sock follows the same ladder. Kart socks are thicker than everyday ones, so if you are buying boots at the same time try them together or allow for it.

Balaclavas

Every kart balaclava we stock is one size and stretches to fit, including the OMP KS and KS Summer, the Sparco Rookie and Softknit, and the Alpinestars Ride Tech V2. There is nothing to choose. If you wear glasses, an open face style is easier to get on without dragging the arms out of place.

What this layer is for

Everything in this category is marked Non-FIA, and that is normal. Kart underwear is a comfort, wicking and abrasion layer rather than fire kit, which is the opposite of car racing underwear. What it does do is stop the suit chafing over a long day, keep you warm in winter, and add padding at the ribs where the seat works on you.

The padded shorts are the ones people underestimate. They sit between you and the seat and they are the difference between finishing a wet club meeting comfortable and finishing it bruised.

Buying a kart suit at the same time?Measure in the underwear, or order it first. A suit sized over a t-shirt and then worn over a long sleeve top and long johns is the most common reason a suit that should have fitted does not.

Falling between paired sizes?Send us your chest and waist with the range you are looking at. The paired sizing here is wide, so it is worth a check. Call 0115 989 3488 or email Sales@GSMPerformance.co.uk.

Sparco bands from sparco-official.com. Alpinestars from the size guide on their Race V3 Top Tech Layer. Sock ladder from OMP’s published racing sock ranges. OMP publish no kart underwear measurements, which is why they are not tabulated. All checked 2 August 2026.

Have you written anything about this exact product?
Yes, we have covered this exact product: Alpinestars Tech 1-KX V3 Kart Boots – Now Available in Two New Colour Options, and OMP KS Short Sleeve Top – Now Available In New Colours for 2025. That is first-hand coverage from our own builds and showroom, not brochure copy.

What is karting underwear actually for?
Comfort and temperature control rather than fire protection. A close-fitting base layer wicks sweat, stops the suit rubbing, and keeps you warm in a February practice session or cooler in August. It is not FIA fire-resistant underwear, which only matters for car racing, and our guide on fireproof underwear rules explains that side.

What size should I go for?
Sizes run from S to XL. Base layers work by sitting close to the skin, so if you are between sizes, take the smaller one.

How do I wash it?
After every session: cool wash, no fabric softener (it kills the wicking), air dry. It is the easiest bit of your kit to keep fresh, and doing so means the suit itself needs washing far less often.

Availability

Alpinestars comes from central distribution

All Alpinestars goes through central distribution. Stocked items take around 10 working days.

Special order items

Items we do not hold extend to around 20 days.

Before you order

Give us the item and the size you want and we will tell you which position it is in before you buy.

At GSM Performance, our priority is to maintain the utmost hygiene and quality standards for the benefit of our customers. To that end, we have instituted a policy that all purchases of long johns, balaclavas, tops, and underwear are final and non-returnable. This policy is necessary due to the personal nature of these items, which are worn in close contact with the body. This protocol is intended to guarantee the health and safety of all our customers.

This policy adheres to the best industry practices and safeguards both our customers and our staff. It's important to clarify that this policy does not affect your statutory rights as a consumer. This policy does not apply if you receive damaged or defective products. In such cases, our customer service team is available to promptly address your concerns and arrange a replacement or refund. We greatly appreciate your understanding and adherence to our hygiene policy and thank you for your continued confidence in GSM Performance. For further information please see our terms and conditions which are agreed on checkout.

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