Flexible wood! All of our bracelets are cut from birch, sanded and edge rounded for comfort, formed, and finished with beeswax and mineral oil. The clasps are rare earth magnets that are incredibly strong.
Please note, these are not daily wear bracelets. Though reasonably strong, they are made of bent wood and can be broken if twisted or bent the wrong way. They aren't for rock climbing, swimming, sword fighting, swashbuckling, or hammer time. Wear them for special occasions and they will last just fine. Stretching the bracelets open beyond what it would take to insert your wrist is asking for trouble... though they are surprisingly flexible, they are still made of wood.
There is a special technique to removing the bracelets. It is easily done with one hand if you slide the magnets apart in opposing directions with your thumb and first finger. Do NOT try and pry them apart or you will break your bracelet! Simply slide them and they will easily pop apart.