These are (3) CV Joint Torque Distribution Washer designed for 90 mm diameter CV Joints and for (IRS) classic air-cooled Volkswagen Type 1 vehicles like the Beetle, Super Beetle, Karmann Ghia, and Type 3.
Function and Necessity
These "moon washers" or "spreader plates" sit underneath the CV bolt heads, bridging the gap between two bolt holes. Their purpose is to evenly spread out the massive clamping force generated by the CV bolts across the flange surface area. Skipping them can distort your CV boots, cause grease to leak out of unevenly compressed seals, and let your axle bolts violently vibrate loose. 
Critical Specifications: (Pack of 3)