From their announcement:
Let the “Meat Chopper” do your talking for you the next time your walker meets the enemy.
The kit includes the M45 Quad M2HB .50 cal AAMG mount with a mounting plug for the Gear Krieg General Early Walker kit, plus a seated crewman, letting you field the U.S. M11A4 AA Walker.
The kit will also fit any Company B Stuart tank model.
Look for this kit in the Gears & Guts product line at the Company B website. Gear Krieg is the original genre-making Weird War II dieselpunk setting from Dream Pod 9.