However, there are no wheel or the control lock on the unit or on the foot. It is therefore necessary, on the foot, a flash claw (cold shoe) that allows locking.
Choose a good model in the unit you have. There are Nikon and Canon models (flash claws are different), and Canon, the cable switch depends on the model. The EOS 7D or 5D (for example) have a specific decision while a 1000D will have a mini jack.