Heavy-duty, precision-machined face plates made from bright steel. They have Australia's most common thread size - M30 (30mm x 3.5TPI) cut into the back to keep the cost of the face plates down.
75mm or 100mm in diameter, it measures approximately 36mm from the base to the face of the plate. There are either four (on 75mm diameter) or eight (on 100mm diameter) holes for screwing your work piece on and are 6.3mm to accept the largest countersunk head screws available (14-gauge).