The Skoda ones are the ones to go for. (and 10% of the cost of the genuine Maser bit!!!!!) Cured the parking sensor ills on my old Granturismo.
I think if you have hands like Michael Jackson, and you can unbolt the lower edge of the rear bumper you can get your hands up there and replace the units without having to completely remove the bumper. (I saw Shiltec do this once, so it must be OK