The Tough Board series. Very complete breadboard in compact size. Rugged FR-4 material with Tg-170 rating and 2oz ( normal is 1oz ) copper for multiple soldering/de-soldering. 2oz also provides more power handling. Pads are connected in rows of 5 for faster wiring. We provide separate power and ground pad columns on 2 sides with another separate ground column in the middle which is connected to a ground plane that encircles the entire board. This compact board gives you power handling AND shielding. The top side has round annular rings and the bottom side has square rings providing easier attachment of SMD discrete components. 4 mounting holes .125″ provided on each corner.