Laser cut tool for accurate monitoring of chain wearThis precision tool made by Birzman is CNC machine laser cut for absolute accuracy enabling you to measure the chain tension. Chain stretch can occur over time and replacing a whole chain can be expensive and inconvenient, especially if it breaks or loses tension causing the chain to frequently come off. The way to avoid this is to regularly check for chain wear. This tool enables you accurately measure chain tension and to identify if (and when) a link has undergone chain stretch of between 0.75% and 1.0% of the standard 12.7mm chain link spacing. This tool is also useful for regular maintenance or assembly to hold the chain still whilst you work on it. Size: 136 mm