This spacer set is for use with the X-ray Chassis in conjunction with the 3 spacers that are already included with the chassis. There are three spacers in the kit along with mounting screws which increase the length of pull from 3/8" to 1 1/8" beyond what the included spacers give. With all three spacers in this kit and all three that are included with the chassis, LOP will be approximately 15". Mfg: Kinetic Research Group