Pearce Grip's Grip Extension replaces the magazine base plate providing better comfort and control by adding approximately 1/2" of gripping surface. It does not alter the capacity of the magazine. An optional filler piece is provided for Glock Gen 5 models with the semi-circular cut-out in the lower front area of the grip body. This optional filler piece allows for installation of the PG-19G5 on all Mid and Full Size Generation 4&5 Glocks. This product will only work on magazines equipped with double notches for the ambi magazine release (Gen 4&5 magazines) and that have a capacity greater than 10 rounds. Note: Not for 10 rounds magazines.These grip extensions replace the magazine base plate providing better comfort and control by adding approximately 1/2 inches of gripping surface. They do not alter the capacity of the magazine. An optional filler piece is provided for Glock Gen 5 models with the semi-circular cut-out in the lower front area of the grip body. This optional filler piece allows for installation of the PG-19G5 on all Mid and Full Size Generation 4 and 5 Glocks. This product will only work on magazines equipped with double notches for the ambi magazine release.(Gen 4 and 5 magazines) and that have a capacity greater than 10 rounds. Features: Not for 10-round magazines (PG-19)