The Planted Aluminum Offset Universal Side Mount is made from 1/4th inch thick aluminum to comply with FIA's 13/64 inch minimum, weighs approximately 3.5 lbs, and powder coated grey. These will fit Side Mount Seats offered by: OMP, Cobra, Status, Racetech, Sparco, Recaro & Bride for sure and will most likely fit most other seat manufacturers but have not been test fitted. In most cases you'll want to use the 90 Degree Universal Side Mount. However, when installing a seat that is the same width as the holes you wish to mount to you'll want to use the Offset Side Mount because a 90 degree side mount will not allow you to install the bolts.
An example would be when installing a Recaro slider, which is 16 inches wide, with a side mount seat that is also 16 inches wide. The vertical part of the 90 Degree Side Mount will actually block the holes and not allow you to install the nuts and bolt to hold down your seat. In this case you will definitely want to use the Offset Side Mount.
The Side Mounts are made to bolt directly to sliders but have multiple slots for adjustability when direct mounting (eliminating sliders). Price listed is for Side Mounts for one seat.