Rivets are a common type of fastener. They are made of brass, copper, steel and aluminum. They are used for securing a wide range of materials from steel and aluminum to leather, denim, canvas, etc. Rivets can be found in various sizes ranging from about 5mm to 19mm (0.2 in. to 0.75 in.) long. ... Common Use: 6mm / 0.24 in. Good to use on ...