CYMA 031 (top), 031A (middle), and 028A (bottom)

-- metal gearbox
-- metal foreends, flash hider, rear sight, receiver cover, selector, trigger, & trigger guard
-- ABS receiver, pistol grip & buttstock
-- 8.4 batt, hicap mags
-- scope side plate mount included for the 031A

the 028A is a "tactical" version that comes with rails and a contoured pistol grip

source: gunner airsoft