Cutting-edge engineering gives Sea to Summit:registered: eVent:registered: Compression Dry Sack a clear advantage over traditional dry bags. Using a unique combination of a waterproof 70-denier nylon body and lid, and an air-permeable, waterproof eVent base, this waterproof bag lets you push the air out without the need for a purge valve. This also ensures even pressure distribution, unlike ordinary dry bags that can balloon or pop open from uneven pressure. 4 compression straps provides a minimal footprint, while the Hypalon roll-top non-wicking closure provides a secure seal. Double-stitched and tape-sealed seams ensure waterproof integrity. The Sea to Summit eVent Compression Dry Sack boasts a pull handle on the bottom for grab-and-go convenience. Finished with patent-pending field-repair buckle with stainless steel pins.