Wheel chocks for single axle?

What do you guys use as wheel chocks for a single axle trailer? I've been using a store bought plastic chock in front and back on both sides of the trailer. These seems to move around some and get loose over time. On my previous dual axle trailers, I had a homemade chock made from 2 4x4 wedges that I put in between the tires and tightened a wing nut on a threaded rod.

Thanks!