A later improved version of the Crane stock, the EMOD Stock or Mod Stock as they are more commonly known, features the same 6-position telescopic adjustment and increased interior space to accommodate a rear-wire battery in the form of a tri-stick crane stock battery solution. This mode goes a step further by making the side panels removable so you can reduce the mass of the stock if youa re not using the battery compartment.
With yet more additional space in the form of a small hatch-accessible compartment, it can store miscellaneous odds and ends like AA / AAA / 9v batteries, small Allen/hex keys or even a dozen M&Ms if you so choose.
The stock itself is a very durable, fairly lightweight (though heavier then a standard M4 polymer adjustable stock) piece which hold up well to long term wear and tear. The butt plate is both rubberized and textured to improve grip, hold and comfort to a degree.
The rear stored battery option s is particularly useful in M4s with rail systems as they lack the space to store the battery in the front and externally wiring a battery box is not the neatest or prettiest solution. Also, the rear wired battery helps to pull a bit more weight to the rear of the weapon which goes some measure in balancing the weapon a little better (although not much if you are using a metal rail system anyway). The additional compartment can be handy for holding a spare Allen key for adjusting sights or attaching/removing accessories or even emergency field repairs if so needed.