BR 4,0-Testata lunga concava

Long head for BR, CH and SC.
With long head you must use long mandrel.
With standard head you must use short mandrel.
You have to select a flat or a recessed head according to the king of riveting to be done (more or less rounded deformation of the rivet), and also to the type of material and thickness you have to assemble.

How to choose the standard flat or countersunk head.
Standard flat: to place BR with both dome or recessed head.
Standard recessed: to place BR with dome head only. It helps to shorten the grip range.