An adjustable depth of drive assembly for use with a fastener driving tool, said assembly comprising: a workpiece contact element having a contact end and an adjustment end; a rotatable adjustment member configured for being securable to the tool and being displaceable between an adjustment position in which said workpiece contact element is movable relative to the tool, and a locked position wherein said adjustment end cannot move axially relative to the rotational adjustment member, said rotatable adjustment member engaging said adjustment end whereby rotation of said rotatable adjustment member causes movement of the workpiece contact element relative to the tool; at least one locking detent disposed on said rotatable adjustment member and configured for being reciprocally engaged and disengaged from at least one locating structure on the tool by manually overcoming a spring bias to displace the rotatable adjustment member from said locked position to said adjustment position for securing said adjustment end in a selected locked position relative to a housing of the tool without the use of tools; said locking detent being a raised formation on an upper exterior surface of said rotatable adjustment member; said at least one locating structure is an opening on the tool having substantially the same dimensions as said locking detent for receiving said locking detent and preventing the rotation of said rotatable adjustment member with respect to the tool; characterized in that said rotatable adjustment member further comprises a threaded pin for engaging said adjustment end of said workpiece contact element, which pin is pressure fit concentrically with an internal wall of said rotatable adjustment member. a workpiece contact element having a contact end and an adjustment end; a rotatable adjustment member configured for being securable to the tool and being displaceable between an adjustment position in which said workpiece contact element is movable relative to the tool, and a locked position wherein said adjustment end cannot move axially relative to the rotational adjustment member, said rotatable adjustment member engaging said adjustment end whereby rotation of said rotatable adjustment member causes movement of the workpiece contact element relative to the tool; at least one locking detent disposed on said rotatable adjustment member and configured for being reciprocally engaged and disengaged from at least one locating structure on the tool by manually overcoming a spring bias to displace the rotatable adjustment member from said locked position to said adjustment position for securing said adjustment end in a selected locked position relative to a housing of the tool without the use of tools; said locking detent being a raised formation on an upper exterior surface of said rotatable adjustment member; said at least one locating structure is an opening on the tool having substantially the same dimensions as said locking detent for receiving said locking detent and preventing the rotation of said rotatable adjustment member with respect to the tool; characterized in that said rotatable adjustment member further comprises a threaded pin for engaging said adjustment end of said workpiece contact element, which pin is pressure fit concentrically with an internal wall of said rotatable adjustment member.