The Blackburn Outpost Elite Universal Seat Pack (USP) was designed to work with dropper or standard seatposts, be able to carry a bevy of cargo, and be stable enough to not swing around while it does. The USP is a two-part system: Part 1 is a T6061 Alloy Wing that affixes to your saddle and works with a standard or dropper post. Part 2 is a removable and waterproof dry bag. The bag has a scuba-style air bleed valve to assist with compression while off the bike. The wing stays on the bike, the bag comes off and allows you to pack, compress and go ride in the snap of a few buckles. Features: Dropper post compatible T6061 wing bolts attach to seat rails for a solid mount Outer harness system allows inner bag to be removed without detaching harness from the bike Scuba-style air bleed valve for a tight pack while remaining waterproof Welded seam construction maximizes waterproof performance Stable no-sway design allows you to carry cargo with minimal effect on bike handling Specifications: Pack Type: Cargo Saddlebag Pack Capacity: 5.25L (6.95L When Expanded) Mount: Aluminum Mount & Harness Waterproof: Yes Material: - Dimensions: 14 x 6.5" (Standard), 19 x 7.5" (When Expanded) Color: Grey Weight: 572g Shop our selection of Blackburn Outpost Packs & Racks.