Designed to work exclusively with MAXTRAX XTREME and MAXTRAX MKII. Our Combo pin set will allow you to mount one set of MAXTRAX XTREMEs along with one set of original MKIIs.Only one set is required for mounting one set of MKII and one set of XTREME.For mounting only MKII and MAXTRAX XTREME together: please look here for our MKII Mounting Pins Please Note: Antiseize recommended on install.