Of the ones in the past 5 or so years, the 6721 and a subset of the 6920 models, including the 6920 HBPW (UPC: 098289020543).
You can find some of the other models that are nominally approved ("not banned") on the MD state list here (scroll down to clink on Colt) ... the LE6920HBPW is the Colt AR-15 model M4A1-SOCOM iirc ...