When we first started using our trailer we foolishly bought a set of bright yellow plastic Camco wedges. They turn out to be more slippery than snot on gravel, and we had two very scary incidents where our trailer slipped. I threw them away and bought this wheel chock along with a set of small rubber chocks. Especially with this one, the trailer doesn't move at all. We are on a camping holiday and the caravan next to us has slipped. Of course they used fucking yellow Camco pads. I showed them our block setup. That day they bought a pair of rubber pads and ordered one of them.