These are Pure Gemstone bracelets made with love from Colorado. The hand stamped tags on some of the bracelets are hypoallergenic silver. There are 5 different hand stamped designs and most of them come in a smaller 6.5" or 7" for a medium which is the most common size. There are a few diffuser bracelets with the Lava Rock that essential oils can be added to. The Lava Rock will absorb the oil. There are several colors to choose from!