The hole cutters supplied with these aftermarket sensors are generally 21-22mm, so as Neil says, it depends on the original hole size. You won't be able to use any of the original wiring though. I fitted a set on my Celsior a few weeks ago and they work a treat. I only paid £19 though, £34 is too much, especially as they're not vehicle specific. Easy job really. The hardest part was finding a way through to the cabin from the boot for the speaker wire.