If you want to mount a chain guide on your Ripley (V4), RipMo V1 & V2, RipMo AF, HD5, HD4, HD3, Mojo 4, Mojo 3, or Mojo HDR, you will need one of these. It's aluminum ISCG 05 standard When using SRAM DUB cranks along with this on a RipMo or any frame with a 73mm bottom bracket shell width, you will need the SRAM DUB 2mm spacer inside the drive side crank arm against the bottom bracket shell.