ROHN NP Roof Mount 1.50"OD 30 Inch Height The base of the ballast roof mount is 34-3/4" square with trays to fit the concrete blocks, for ballast mount. The FRM roof mount is hot dip galvanized for corrosion protection and goes together quickly. The ballast roof mount is easily shipped via UPS. No penetration on roof surface. Galvanized for corrosion protection. Designed for concrete block ballast mount. Goes together quickly. Minimum of bolted connections. Optional roof pads or mats are available