http://www.patrolbase.co.uk/airsoft/gate-picossr-3-aeg-micro-mosfet-unit.htm#.Wg-yElVl_IU
or free ship on ebay:
https://www.ebay.co.uk/itm/Gate-Pico-Ssr-3-Power-Control-Unit-Airsoft-Mosfet/222673710258?epid=1908037050&hash=item33d8632cb2:g:9FMAAOSwm9tZ1PLR
https://www.ebay.co.uk/itm/Airsoft-Mosfet-Gate-Pico-Ssr-3-Mosfet-Power-Control-Switch/352182609615?epid=1908037050&hash=item51ffb826cf:g:kdoAAOSwOfBZ1PLZ
http://www.patrolbase.co.uk/airsoft-switches-selectors-and-mosfets/gate-nanoasr-3rd-gen-advanced-solid-state-relay-mosfet.htm#.Wg-yYlVl_IU
or free ship on ebay - think it is an older version of asr - the SSR:
https://www.ebay.co.uk/itm/Gate-Nano-Ssr-Airsoft-Mosfet-Lipo-Nimh-Power-Control-Switch/322699775846?epid=1523096927&hash=item4b2267cf66:g:ErMAAOSwhpZZ5igz
https://www.ebay.co.uk/itm/Airsoft-Aeg-Power-Control-Gate-Nano-Ssr-Mosfet-Lipo-Nimh/132313427260?epid=1523096927&hash=item1ece7ead3c:g:inwAAOSwMQBZ5jsC
Bullseye are sound retailers, ordered bits n bobs from them before and no probs
Patrolbase are also sound but factor in shipping costs
DO NOT BUY AN AVACADO BURST B*LL*CKS THINGY !!!!
it is NOT a mosfet and does NOT protect your contacts etc... as it is plug n play gimmick stuff
(fine if you like gimmicks but it is not a mosfet)
(people say it can be used alongside a basic 3034 but that is two modules - there is a Kong burst wizard instead but tbh nahhhhhhh)
Alternatively the sparklabs one as it looks good, but is so new nobody has tried one yet that I know of
There are also Jefftron mosfets around also from Poland but not tried these
(I'd say Gate are one of the best off the shelf atm and easy to source)
Or if you can solder (which you need to be able to do to fit a mosfet/deans etc....)
Then you can build your own 3034 diy mosfet for under a fiver
(can actually build it for under £3 if buying the few bits in bulk)
http://unconventional-airsoft.com/2009/08/26/how-to-make-a-basic-mosfet-switch/
ensure you buy PROPER genuine 3034's from RSWWW or Farnell etc....
buying cheap 3034's from fleabay China seller will result in you getting fake 3034's that blow very quickly
the genuine IRL3034 mosfet is a tank of a mosfet if done properly/neatly (if you can be ar$ed)
make a few up at a time is best advice for upcoming builds
Or just buy a £10 to £20 Gate mosfet off the shelf for a one off build
Pico is tiny & slim, from a good company - guess it depends on where or what room you have to play with
Other Gate's with deans means you could fit a basic SSR/ASR and remove/upgrade to a bells/whistles Warfet if you wanted
easy to remove/replace on the deans connector & mini plug but a bit larger than the pico
Most install problems is either down to sloppy install - bad messy wiring and/or poor insulation = shorts
Plan your wiring carefully, take your time, ensure everything is insulated, practice clean soldering = walk in the park
(that is easy to say now but my first one or two were not my best pieces of work I'll admit)
watch some vids on youtube will help for soldering tips & other stuff
Oh and use decent soldering iron/solder/flux maybe blah blah blah
If you have a v2 gearbox that is NOT re-enforced at the rear (G&G, VFC and some others...)
If you walk on water and are an absolute legend then you can perform this amazing install...
NB: not my work, this guy is a real clever mofo that I bow to his genius ingenuity....
I tried it once and it was insanely difficult to squeeze it all in
not sure if guy used a TVS diode (advised to fit one)
might have used a smd one right up top left but hard to tell
but it was a damn headache to do and I needed to angle it more, use glue/hot-glue to keep it there
(sod that, I'm sad & like a challenge but also know my limits of what I can be ar$ed with)
If you have a v3 gearbox then very likely you can fit a mosfet without needing to open up the gearbox
whooooaaaaaa - went off on one yet again - my bad