Thanks guys. Is it necessary to use 2 chocks, one on each side, or will chocking only one side keep it from moving?
I use 2. That helps alot. Mine are lockable also. Because my Surveyor has a "skirt" on the top of the wheel well and 14" tires there was not enough room to get the other types in and then adjust them. The roto chocks are adjustable from the outside.
Take a good look before you buy anything. I have been trying to give my "X chocks" away because no one would buy them. No takers yet.
Measure twice and buy once.