need some new U-bolts...

Quick question, the originals had a flat on the inside of the U with a cross hatch pattern. What was the purpose of it, and is it necessary? Was it just something to do with the manufacturing process or did it have a purpose, like spreading the clamping force/flat to flat clamping area/keep from slipping? I just bought a set from Mancini, for about $40. To the OP, ESPO has cheaper ones, $4 each. Just wondering if I could have saved myself some money.