Effective and reliable StepLess design This special design eliminates steps and/or overlaps on the inner circumference of the clamp. Because the tongue resides in a groove, the tongue-in-groove" feature exerts pressure on the assembled parts over 360 degrees. This enables the clamp to apply a continuous radial force completely around the connection s diameter. Oetiker Clamps and Rings are manufactured to metric dimensions. For identification purposes, the nominal diameter is stamped on each product. To determine the correct clamp diameter, push the hose onto the attaching material, (e.g. the nipple), and then measure the hose s outer diameter. Select a clamp whose average value of the diameter range is slightly greater than the hose s outer diameter. Requires model # 10520054 Jaw Pincer Pliers