The Profile Signet guard sprocket is manufactured from 6061 Aluminum and is made by Profile Racing in the USA. This sprocket is a unique universal fit, It uses an adaptor insert that comes in a range of sizes to fit your cranks in either spline or bolt drive. We offer the insert option as a free gift with this sprocket. The insert is made from Chromoly steel and can be added to your basket as a free gift ###section### Product Specs TYPE: Spline Drive MATERIAL: Alloy WEIGHT: 125g / 4.37oz