Oh man, no kidding... these grips are great! I have the oem heated grips on my k100, and the diameter for both sides is 24mm. However, the pro grips come in 24 and 22mm. I used the 24 for the throttle and the 22 for the clutch side. I lubricated the clutch side heated grip with the blue bottle of liquid wrench lubricant (a.k.a. wd40) and it slid it in perfectly. Once the lubricant dries up, it should be tight enought to stay in place. No need to buy two sets.