My experience with the BAL Delux Chocks wasn't as positive as JDs. No matter how tight you got them they could slip, but there still wasn't any danger of the trailer rolling away. They also rusted, something the Roto Chocks shouldn't do. After using the BALs for about 2 1/2 - 3 years I gave them away and bought some Roto Chocks. They both cost about the same, for the money I like the quality and stability of the Roto Chocks better. I unerstand that Newmar uses them on their assembly line to stabalize their trailers as they are being built.
FWIW
Fireman