I tried the viper flex 5th leg on a set of Bushwear sticks, it goes on fine but is a little loose allowing it to slide up and down - as previously mentioned a couple of layers of tape would do the job. That said, as I was in the shop I tried a set of viper flex and (the wife wasn’t there) promptly bought them. The Bushwear sticks height adjustment is at the bottom, allowing some flex if extended (if you’re tall like me), whereas the viper flex height adjustment is mid-leg making them far more stable. As you say, not cheap though…