Motion Pro Slacksetter Pro - Chain Slack Setting ToolAccurately and quickly measures chain slack. Features: Two scales measure both chain slack and chain to swingarm clearance Setting chain slack properly dramatically improves chain life Lightweight compact design fits easily in your tool box or road kit Works on most street and dirt bike applications up to 75mm chain slack Made from engineered nylon with aluminium measuring scale Anodized laser etched precision measuring scale Refer to your owners