i have a A&K c-mag (its a S-mag) for my MP5, full electric, auto winding/sound activated/pressure pad etc etc
came with everything you need ... except an instruction manual <_< :angry: not to worry as there is plenty out there and they all seem to work the same :lol: :lol:
i cannot remember where i got it from, it may have been Tiger111HK (if your a subscriber there is a discount code in the members forum), and if memory serves it it came to less then £50'ish
few points to note/tips, i needed a plug adapter to charge it, only charge it for 30mins at a time .... one charge lasts a long time (no idea how long as i change weapons abit) ... and remember to turn it off when not in use (i have mine in sound activated normally) ... to hold the flap open on the drum i use an old hop rubber :lol: ... there is NO manual wind system (on mine) so if it buggers up, have a backup mag of some description
other than the small filling hole in the MP5 version, mine has yet to let me down