I have just try to install a new small ecu for my ptw clone, ctw m4a1 in order to use magpul stock on it.
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really small...
first, remove parts like grip,grip end, old ecu.....
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unscrew the stock tube and size compared with ecu mosfet unit and 11.1 firefox battery
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remove old ecu and install new ecu
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also a new elc-001, software programmable full atuo and 3 burst
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almost finish...battery inside..
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finally, a magpul stock on my ctw :cheers::cheers:
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