The PTS EPS features a rubberized removable buttpad for comfort and a slip-resistant grip. Fixed side storage compartments offer enhanced comfort and a consistent cheek weld.
The side storage compartments measure up to 139 x 31 mm of spacing so you can fit 2 piece butterfly style 2/3A cell NiMH batteries or Lipo batteries to power your electric airsoft gun or you can use the compartments for AA, AAA, CR123A battery or miscellaneous parts storage. Additionally, the rear portion of the stock can fit a 9.6V NiMH minibattery or a LiPo battery of similar size as well as be used for miscellaneous storage. 
There are multiple sling mounting options featured on the stock including QD swivel sockets on both sides with a pass-through channel for loop-type sling attachments and a sling slot on the front side of the butt part of the stock.
The EPS Stock is compatible with almost all AEG and GBBR buffer tubes.Features:

Ample spacing for your tools and batteries
Unique cheek welds for maximum comfort
Two different types of ambidextrous sling mounts

Specification:

Color – Dark Earth
Material – Dupont(TM) Zytel(R) High Performance Reinforced Polymer
Dimension – 205 x 135 x 63 mm (without packaging)
Compatibility – 1.148” dia. mm Airsoft buffer tube