I've used leather ones for YEARS. The biggest
problem is that you need to clean it often. You can clean with just water and
then once and awhile, you need to put some leather conditioner on it, to prevent
cracking. I have a neoprene one (Old Orthoflex Angie...the ones hard to find)
but prefer ones that have the adjustment buckles at the Y, where it attaches to
the tail piece itself, not the loop and snap like the neoprene ones I've seen.
My new favorite is the plastic tube and biothane I got from Canadian Tack. Many
of the plastic tube tail pieces are not pre-shaped and curved to lay nice under
the tail. They are just a piece of tube looping around, and they kink, don't lay
flat etc.
Scroll to bottom to see crupper. I had mine made
without the snaps, and just the buckle in adjustment. Paddi (as most of the
vendors) is great to work with. The plastic tube cleans easy, no maintenance.
Oh, is this where I say "My horse and I love it". (I don't think any horse LOVES
any tack if given a choice, they would be fed, fussed over, and not have to wear
tack at all) ;-)