This is the RHT-380 adapter from SnowEx. This is the same as the Fisher and Western 75915 for the Fisher Speed-caster 525 & 900 and Western Pro-flo 525 & 900.
To install an SP-1875 on a 2" receiver hitch, you will also need adapter RHT-085.
To use this with an SP-1075, you do not need anything else.
It weighs 84 lbs and measures 9" x 19" x 30".
The parts list and installation instruction can be found at this link.
