Tdi rail covers are great - Tdi Arms Tactical Rifle Rail Cover Kits

I really like these rail covers. They are a very grippy rubbery material providing a great grip. They are flexible, so you can twist and manipulate them onto your pic rail easily. They even have the "lock bar" molded on for pic rails, so they will not move or slide on the rail. Color was very close to the OD I already had on rifle, though I cannot confirm if it is Magpul ODG or not.

If I had another quad rail, I would definitely purchase these again.