Seattle Sports Standard Canoe Foam Block - Pair
This pair of foam blocks from Seattle Sports is a replacement set that does not include straps or other tie downs. Includes two standard foam blocks for canoes. Designed to fit directly on a bare roof. Rubberized non-slip bottoms. Dimensions: 6" long x 3-3/16" wide x 3-7/8" tall. Manufacturer's part number: 068622
CargoGear Reviews

Written by A2canoer, on 6/30/2015
I used these blocks to haul a canoe on top of a Chevy Impala along with 2 spare blocks my dad had lying around. The blocks my dad had were similar but had some non-slip grip material on the bottom which is nice. But these definately did the trick and the canoe didn't move an inch during the 3 hour drive. They are made of sturdy foam and slip easily onto the gunnels of the boat, could use on any car as cushion for the boat or even a truck if you needed it to rest on a "sensitive" area like paint.