The RAM-D-162H-MC4 (RAM McMaster Carr Swing Horizontal System) is a RAM D sized horizontal ratchet extension system with 2.25 inch diameter ball.
RAM-D-162H-MC4 shown above.
RAM-D-162H-MC4 Included Features:
Warranty: Manufacturer's, RAM Mounts (National Products Inc.), Limited Life Time Warranty.
Size: Compatible with RAM D sized parts / Max. Weight 15 lbs.
Material: Black powder coated marine grade aluminum.
RAM-D-162B-DU Ratchet Base with Ball Description:
The RAM-D-162B-DU is a ratchet base with RAM D sized 2.25 diameter rubber ball. The ball can attach to other RAM D sized accessories with an open end socket. The ratchet side of the base attaches to the RAM-D-162AU. 
RAM-D-162AU Long Ratchet Swing Arm Description: The RAM-D-162AU is a 12 inch long ratchet swing arm. The ratchet side attaches to the RAM-D-162BAU and other side to the RAM-D-162SU swivel base.
RAM-D-162SU Swivel Base Description:
The RAM-D-162SU is a swivel base with ratchet arm. The ratchet arm side
of the base connects to the RAM-D-162AU ratchet arm and the other side of the base connects to the RAM-D-162HU base.
Horizontal Base Description:
The RAM-D-162HU is a horizontal mounting base that attaches to the RAM-D-162SU swivel base.
