The Q 3000WB/WB50 are an L-shape:
The panel which attaches to the wall is 150mm x 60mm with 5 x 5mm dia. fixing holes and a 25mm dia. hole for cable entry.
The section supporting the speaker extends 90-125mm from the wall depending upon the angle the speaker is fixed at.
The screw hole centres of the Q 3000WB/WB50 are 40mm x 110mm apart.
The centre of the 25mm dia. hole for cable entry is 15mm above the bottom screw holes on the centre line.
22mm of thread protrudes through the 3000WB/WB50 which would then screw into the loudspeaker insert, the pitch of a standard coarse thread M8 would be 1.25mm.