These brackets are exceptionally good quality. They can support a 1" diameter mast/tube either horizontally or vertically. The base measures 4" x 1 3/4" (100mm x 45mm) with a height of 60mm from the base to the edge of the bracket. The bracket is made of good quality galvanized steel, which is 2mm thick. The hole pitches are centred at 85mm apart on the long side and 30mm apart on the short side. These are very robust brackets and I have bought several of these for Amateur Radio projects. Excellent value for the price.