Amcraft’s Easy, Accurate Multiple Window Installation System Our SnapTite Field Mulling System makes it a snap to install a configuration of windows on site. One person can safely load, handle and attach each unit – without any special trucks, material handlers or damage during shipping. Reinforcement can be added to the head and jambs of most units by inserting 3/4" stock between the units. The SnapTite mulling strip, attached to a trim leg on the frame’s inboard or outboard side, adjusts to create the perfect mulled unit.