ETP bushes consists of a thin walled cylinder filled by a 'medium'. When this medium is pressurised, they tend to expand the thin walled cylinders and grip both the shaft and the component at the same time. To mount any product onto a shaft – Position the ETP Bush on the shaft/product, & just tighten the screw. This tightening increases the pressure on the medium which expands the inner/outer walls of the Bush to grip the shaft and the component simultaneously.