The 5DEV 104BCD BMX Spider is what you need to complete your RGXC Titanium BMX Crank set up. These cranks are all SRAM 8-bolt interface design and any BMX 4 bolt chainring can be installed to the RGXC cranks with this spider, though we highly recommend using BMX chainrings from manufacturers such as Tangent Products and Rennen Design Group to ensure a matching level of high end products.