Double Eagle M904 M4 with Falcon Fire Control System (Black - M904G)
front to back
14mm neg thread 
polymer m lock front
quick change spring under the battery box 
fire unit trigger type progamable with pulls
sets trigger 1mm-3mm settings
fire on pull and release of trigger
1-5 shot burst instead of full auto
comes with full instructions 
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flip up sights
comes with 120rd midcap magazine
ambi fire select 
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stock will come off easy to fit battery in stock box at back
no battery or charger with gun 
advise a stick 1100 mah 11.1v stick lipo
this seams to fit nice
great rate of fire and even gives you 5 beeps at 3v 
so you can change out the battery
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this is one of our best selling bb guns at the present time