The 124 GPM suction fitting that meets the Virginia Graeme Baker Pool and Spa Safety Act of 2008.  The 124 GPM suction is IAPMO listed with a flow rating of 124 GPM.

The extraordinary rating on both suctions is higher than any other equivalent sized suction on the market prior to the VGB legislation.

The 124 GPM is about 3-3/4 inches (9.53cm) in diameter. The smaller size fits the smaller recesses by reducing the need to modify any moulds in order to make the larger suction fit. The smaller hole has a size of 2-3/8 inches (6.03cm) with a flat gasket.

The 124 GPM suction connects to 3/8” (.95cm). The tubing should be positioned to rise up under the lip of the spa. When the suction cover is obstructed, air is pulled
through the tubing, cavitating the pump so its loss of prime and water flow is minimised.

Balboa Water Group's VGB suctions are patented under U.S. Patent No. 8,191,183.