These are the original type of shaft clamping elements, proven in a wide range of applications for more than 20 years. Suited to more general applications, this series provides medium torque transmission, which can be increased by mounting the unit in series. This type does not provide self centring, and therefore other methods of centring the hub to the shaft are required. The units do not move axially during clamping and generally self-release when clamping screws are relaxed.