I have lots of straps and tawses. Strapping can leave quite nasty marks if you have a hard edged leather and I have a few of these and a few that have a softer edge so I can keep going longer without marking so much. I have a very nice one wih a handle which means I can hold it tighter for a harder hit. I also have my prison strap is a rather mean thick leather strap which leaves a nasty sting.
My favourite tawse I have is a light tan leather two ended tawse, it's really smooth and delivers a good hit, time after time.
See some of the bottoms I have strapped and tawsed on my Bottombook.