Shimano SM-CN910-12 Quick Link 12 Speed (Includes 2 Pairs of Links)

This was the best price on the market - delivered - for these quick links which work just as Shimano stuff should. Be warned though that the force required to lock these into place is huge. It took me and my strapping 15-year-old son holding one handle each on the chain tool pliers to lock them into place. It says on the box 'single use only' so I can't see them coming apart at any stage!