The RPM-Q2R20120-01 designation makes tracking simpler, and you will find that very helpful.
898H-1CH-D1SW-R1 12VDC Automotive Relay, 50A, 12VDC, Form 1C, Weatherproof (Pack
A nice touch is the subtle notch on the BU1 AC that lines up with the base each time.
A nice touch is the heavy duty casing, which lines up with the switch control and makes daily adjustments feel easy.