I new this would be a tough one. I thought it would be fairly quick and easy to find the rubber material on the web, but I spent several hours last night searching without much luck. I found similar rubber strip material, using keyword searches such as: U-channel, C-channel, J-channel rubber edge trim, etc. The edge trim is actually J-Channel stock. That appears to be very hard to find in a flexible rubber material. I know it can be made, but I just want to buy about 4 feet of something that is the same, or just slightly different. I don't know the reasoning for the use of J-channel, rather than U-channel. Maybe the shorter "leg" allows the material to bend better for curves. Believe me, I found lots of other edge trim strip material, but nothing that was close enough (especially in size and profile). Of course I'll keep looking, but how much effort can I endure searching for this material for a measly 4 feet. I've attached a photo showing the profile, and a quick sketch of the dimensions.