KMC 1/8" half link
This extremely handy little dandy will add or subtract 1/2 a link (1/2") from your chain, allowing you to move the axle 1/4" forward or backward to dial in chain tension or slam that rear wheel.
Available in two versions - black works with all standard 1/8" KMC chains, nickel plated works with K1 Wide (K710) and K1SL Wide (K710SL) chains.
The standard (black) version is also compatible with Izumi 410 and Miche 1/8" track chains.
• for use with 1/8" chains only