Description: 100% Brand new and high quality! Narrow-wide tooth profiling prevents chain drop without a chainguide √Process: Full CNC CNC engraving and milling, anodic oxidation, full of the laser marking √Function: Minimize the probability of chain, simplifying the variable speed system, minus the excess weight It is protable and durable. Easy to use and to operate. Positive tooth corresponding chian tooth width; tooth corresponding negative chain is narow. Suitable for most of the Shimano BCD Models,and some FSA, Sram models. Like:SHIMANO M391/M430/M590/M610/M615/M670/M675/M770/M780/M785/M980/M640/M820 Specification Brand: DECKAS Color: Black/Red/Blue/Gold/Green/Silver Shape:Round/Oval Material: 7075-T6 Aluminum alloy BCD: 104BCD Chainwheel Teeth: 30,32T, 34T, 36T, 38T,40T,42T,44T,46T,.