Material: The spring carabiners are made of 304 stainless steel. They are waterproof, rustproof, corrosion resistant, strong and durable. Link Size: M4/4*40MM length 1.61'' (see detailed figure 2 and 3). They include 7 universal spring carabiners and 3 snap hook carabiners with safety buckles. Wide Uses: The spring carabiners can be used for outdoor hiking, fishing, camping, traveling, children's swings, gym, hammock hanging, pet rope, connecting sports bottle, backpack, keychain/keyring, DIY tools, etc. Wide Uses: The spring carabiners can be used for outdoor hiking, fishing, camping, traveling, children's swings, gym, hammock hanging, pet rope, connecting sports bottle, backpack, keychain/keyring, DIY tools, etc. NOT FOR CLIMBING: The spring carabiners cannot be used for safety equipment, such as rock climbing, mountaineering, ice climbing, and high-altitude play, or any other activity that may result in personal injury or property damage.