The Carbtune II is a synchronizer that is easy to use and is simply connected to the intake side of the cylinder. The vacuum in the intake duct pulls the two polished steel pins (no mercury used!) upwards to show the level of synchronization. Alongside the technical advantages, synchronization is really good fun as it is easy to understand and you are immediately rewarded with a positive result. With high-quality storage bag, operating manual and all of the adapters required.
A manual is available at: http://www.carbtune.co.uk/inst.html