Metal and Wood Brain Teaser 6 Set for Kids and Adults - All the coils and blocks are smooth and have NO SHARP EDGES for endless play without getting hurt. The links are made from heavy-duty 4.5 stainless steel as well as lightweight and durable beech wood that doesn’t easily bend or break even when thrown or stepped on. Players can’t force them open so there is no chance of cheating. It has also passed the ASTM F963 International Toy Safety Standards and guarantees it’s top-notch quality.
