Model RD M310 Compatible with: 7/8 speed; Crown max: 34T. Total capacity: 43T effect of the front derailleur top normal (traditional); length of K figure: long. Extends the advanced, lightweight action design with Teflon-coated bushings and direct mounted rear derailleurs. Material:Made of high quality steel materials, durable and long lasting. Easy to install and remove. Application: Suitable for MTB mountain bikes, road bikes, variable speed bicycles, folding and city bikes. It is your indispensable bicycle accessory for your bike tour.