Half links for adjusting 1/8" Single-speed type chain lengths
Cranked Links (otherwise known as ½ links) allow smaller length adjustments for Single Speed and hub gear type chains.
Connex by Wippermann offer 2 main versions of Cranked Links to fit 1/8” chains:
Cranked Link 108 
Colour: Nickel plated
Compatibility: Standard type 1/8" Connex chains 100, 1Z1 and 108
Cranked Link 1R8/1E8 
Colour: Nickel plated
Compatibility: Heavy Duty 1/8" Connex chains 1R8 and 1E8