Button Type Profile Tool.

SRDCN toolholders use round inserts. The 10mm square toolholder shank uses a 5mm dia insert; the 12mm square holder uses a 6mm dia insert, and the 16mm square tool uses an 8mm dia insert. These extremely versatile 'button' tools are particularly useful where deep profiles are to be produced, and often where other types of tool can't gain access. The cutting inserts are also very inexpensive.

Shank size 10 uses Insert Type 6 - Shank size 12 uses Insert Type 7
Shank size 16 uses Insert Type 8