Got this one for my WE SCAR since holding that well machined Picatinny rail is asking for your fingers to be sliced off, literally. Initially I thought these wouldn't hold on well and I may need to get another set, they were surprisingly sturdy, and also easy to cut if necessary. Goes really well with my AFG 2 I also got recently, holds very comfortable now even if it increases the SCAR's profile a good bit.
An absolute b*tch to install, but once you get them on there they look and feel great. Easy to cut to whatever size needed. I was able to cover all the unused rail space on my SCAR-H, and still had a full strip left over. Can't beat the price either, plenty of retailers charge $10 for ONE cover, this one comes with four.