D-Boys 20mm RIS Sectional Armor Rail Cover Panel 4pcs Set Tan
[AS3640]

It looks cool, but the locking panel doesn't fit standard RIS rails. This causes the entire cover to slide off with ease. I tried placing this on a few different rifles and RIS rails, and it didn't fit any of them.
The only way I can see anyone getting this to stay in place is with glue, tape, or placing it behind/between attachments that are firmly locked in place.