Sea to Summit Ultra-Sil Pack Liner

It is highly water-resistant and features fully seam-sealed construction, making it reliable for keeping gear dry in rain or wet conditions. However, it is not designed to be submerged in water, so it should not be used as a dry bag for water sports.

The 50L capacity is designed to fit most standard backpacking packs of similar volume. Because it has an oval base, it is shaped to mimic the internal contours of a pack, which helps it sit snugly without creating awkward bulk.

This liner uses a unique system where the fabric folds in and secures with velcro before you roll it down. This adds an extra layer of security and creates a more compact, reliable seal than a standard roll-top closure.

It is made from siliconized Cordura, which is known for a high strength-to-weight ratio and resistance to tears and abrasion. While it is lightweight, it is robust enough to handle the rigors of standard backpacking and hiking.

The slippery finish is intentional; it allows you to slide the liner into your pack easily, even when it is fully loaded. It does not affect your ability to organize gear inside, but it does make the process of packing and unpacking your main bag much smoother.