One of the stand-out features of the UTG Sport Model 4 lineup was the optional handguard / RIS which had a trap door mechanism designed to allow you to run a truely massive NiMH battery pack. To my knowledge, this was a unique item.
~2008 UTG Sport Model 4 reconfigured for CQB. This particular one has a 4" tubular handguard with a recessed TM tracer unit that's been modified to hold a UVT 106 2.0 in the front with a open chamber in the back. Currently DSG, all Lonex Maxx etc.