ImpressArt® crystal compression rivets (sometimes called snap rivets). Alexandrite is a traditional birthstone for June. 6mm round head, 3.5mm diameter (just over 1/8") post, 7mm diameter cap. Fits material approx. 3.5mm thick. 5 sets per pack. The rivets fit in a 5/32" diameter hole when riveting metal. For leather, make a 1/8" or smaller hole to ensure the rivet won't pull through. Dress up your designs with these sparkly rivets.