“Weaver Standard 6″ High Swivel Dinghy Chocks with 3.5 x7 Pads C1207
A set of 4 standard chocks 6 inches tall that swivel in any direction and can be adjusted up by using spacer bolts up to 4 inch taller with 3.5″x7″ pads.”
Says the internet.
I purchased these used with the intent to cruise. They don’t appear to have ever been used.