Optics: Slitviewer Mirrors
SV1 is a flat. SV2 and SV4 are concave spheres, both with 668 mm radii of curvature. SV3 is a convex sphere of 334 mm radius of curvature. These form an Offner relay that redirects the light from the reflective longslit to SALTICAM.
Unfortunately, SV2 was not made to specification. It should have had the edges chopped so that it was only 166 mm across one dimension; instead it is a 220 mm diameter circle.