Great belts. No noticeable slippage. They do get loose if you tighten them around your waist and it slips ounder your belly. That isn't the belts fault. It would happen with a regular leather belt too.
I bought 2 double ply (OD Green and Black), and one single in grey.  The doubles are stout. The single is a little more comfortable.
I bought 44 and I wear 42 pants.
Problem with the doubles is I keep losing weight.
Excellent customer service.