The original wired nut that helped launch the clean climbing revolution has continually evolved to remain the standard by which others are judged. Black Diamond Stoppers' 7075 aluminum alloy is durable yet has plenty of bite to sit in rock ranging from bulletproof granite to sandstone. Anodized by size for quick identification, Stoppers have a unique transverse taper that increases surface area contact to provide the best placements in non-parallel cracks. Sculpted and optimized for easy placement and removal, Stoppers® have rounded corners that don't get hung up on crystals and irregularities. Stopper Set: Our anodized Stopper Set includes sizes #4 to #13 and comes with an OvalWire biner for easy racking. The Stopper set is perfect for climbers starting to build a rack or for those adding to what they already have. Features: Time-proven design is light, strong and easy to use Transverse taper allows good placements in funky cracks Anodized for easy ID