The PTS EPM M4 Magazine (ERG) - 3 Pack is a set of airsoft magazines specifically designed for PTS ERG, KWA/KSC RM4 Series ERG/AEG3 rifles, and features an adjustable capacity between 30 and 120 rounds. 
 
Product Details
Capacity: The unique feature is a switch on the bottom of the magazine that allows the user to easily adjust the capacity from a realistic 30 rounds to a 120-round mid-capacity, suiting different gameplay scenarios.
Material: The magazines are constructed from a durable Dupont™ Zytel high-performance reinforced polymer, known for its robustness.
Design:
Features recessed panels and texturing for an enhanced grip.
Includes unique magazine well guides that help reduce snagging when drawing or inserting the magazine into pouches.
The baseplate has a dot matrix pattern for personalization and alphanumeric marking.
Compatibility: Designed for the PTS ERG and KWA/KSC RM4 Series ERG/AEG3 rifles. Note that it is different from the standard EPM 150-round AEG magazine which is widely compatible with many M4 AEGs.