These sacks are ultralight - made with 30D hybrid sil-nylon CORDURA™. Vent means it purges air through the eVent bottom. Dry means it’s factory seam sealed with a roll-top closure, the rolling stay is pre-curved so that it pops open, making it easier to load than a flat stay. Bloc means it nests inside your pack well. Solid means it’s durable, and also that you can compress your gear down to a nearly rocksolid state. But the name doesn’t quite say it all, it's even lighter by replacing the compression webbing with paracord. Granite Gear calls it LineLoc Technology, another Granite Gear first.