Why you should do it:Due to chain wear, expensive rear cogs and chainrings will increase in wear and eventually this will happen. Therefore, regularly checking for chain wear can prevent problems with shifting performance.Replacing worn parts is more economical than replacing them altogether and can save you money. Length:140 mm/5.51 in. Weight:32.8 grams/0.07 lbs. Easy to operate:Simply place the chain code on a section of the chain and check to see if the code is completely flat against the chain. If it is flat, replace the chain. However, if the code is upright at 0.75 percent, the chain will still work. This precision laser cutting tool is carefully crafted with high quality materials, well thought out and focused on durability and easy storage. If you are still looking for a chain checker, this 2-in-1 Chain Wear Indicator Tool will fulfill your needs and is undoubtedly the right choice for you! Compatibility: This chain checker is designed to accurately measure chain elongation up to 0.75 percent or 1.0 percent and determine if the chain needs to be replaced. Compatible with 7 to 12 speed chains