Spinelock Seat BagDescription Revelate Designs set out to create the most stable, low profile mounted, feature loaded, waterproof seat bag available. The Spinelock seat bag checks all the boxes. The Spinelock integrates user tested and approved features like a one way air purge valve, rear light slots, loop and bungee deck, and an external plastic bottom with a new patented attachment system. Stability was the driving element in the design process. If you want