These external bushes are individually machined from 100% PTFE rod. The wall is thin where it goes over the pole tip, to allow them to expand easily for the perfect fit. Inside the bore there is a special shoulder that ensures a smooth transition between your pole and the bush, eliminating any potential of elastic damage. There are other bushes on the market that cost less but they are often made from nylon, which will cause elastic wear, so ensure you buy quality 100% PTFE like these and use Hi-Viz Pure lubricant for a safe set-up. Available in various grades/colours.