I’ve tried perhaps half a dozen commercial strap-on comb raisers and they all failed dismally, either because they didn’t stay put or because they didn’t get you up high enough, or both. I have one rifle that requires a 2-inch lift if I’m shooting it prone. So I bought a surplus closed-cell-foam ground pad, such as is issued to soldiers and Marines and similar life forms, and cut two rectangles out of it that measure roughly 5 inches long by 4 inches wide. (I am assured by a recently-retired Army captain that these ground pads perform much better on rifle stocks than they do on the ground.) I tape the first one in place, and if that doesn’t give me enough height, I cut a small chunk out of the second to accommodate the bolt when I pull it back, and tape that on. When I clean the rifle, I untape the top pad and swing it aside to I can get the rod into the barrel without bending it upward.