Alpkit Sigma

15,000mm waterproof rating.

Waterproof15,000 mm
Breathability10,000 g/m²

£179.99

Price includes VAT · free delivery to mainland UK

30 days to change your mind. Unridden outdoors, so it is still a new bikeUnworn outside, with the tags still onUnused — pitching a tent in the garden to check it is fine — full refund, any reason.

  • 2–4 working day deliveryFree to mainland UK; Highlands, Islands and NI carry a charge.
  • Manufacturer’s warrantyTerms differ by brand and by part — ask and we will send the exact terms for this product.
  • Not sure it is right for you?Ask us first — we’ll tell you straight.

Why this one

A fabric is generally called waterproof at 1,500mm; this is rated 15,000mm. 4 jackets in our range are rated higher, from £199.99.

Full specification

Hydrostatic head 15,000 mm
Breathability (MVTR) 10,000 g/m²/24h
Sizes S, M, L, XL, XXL

Questions worth asking before you buy

What does the waterproof rating mean?

Hydrostatic head, in millimetres, measures pressure resistance in a laboratory. Roughly 1,500mm is the threshold for calling a fabric waterproof; most of ours are 10,000 to 30,000. Above about 20,000mm, breathability and taped seams matter more than the number. See our guide.

Why do some jackets show no rating?

Because they are not waterproof shells. A windproof, a fleece or a canvas overshirt has no hydrostatic head, and quoting one would be inventing it.

How does the sizing run?

Shells are cut to layer over insulation, so they feel roomier than a t-shirt in the same size. Sizing is the manufacturer’s own; ask and we will send the chart for this garment.

Can I try it on?

Indoors, over what you would actually wear it with, exactly as you would in a shop. Once it has been worn outside it cannot be returned.

Not certain this is the right one?

Not sure which one? Our finders narrow the range down to what actually fits what you are doing.

Free UK delivery

2–4 working days, mainland UK

Manufacturer's warranty

Terms differ by brand — ask us

30-day returns

Unused and unworn, for any reason

UK-based support

A real person, within one working day