There's a glut of crimping tools to buy online to crimp RJ-11 plugs but this is the only tool that I could find to crimp BT 4-way plugs. Hence it's purchase.
I bought it from the excellent marketplace seller, Lindy as I needed it to crimp BT plugs onto telephone cabling as I'm improving my internal telephone/SOHO system. As a bonus it also crimps the aforementioned RJ-11 plugs to make off various lengths of "patch leads" to connect modem routers to telephone sockets.
It's made well, has a solid feel and it's action makes it a dream to use. Definite recommendation if you have lots of use for it.