The internal components of these ground blocks are much different from a standard frequency VHF/UHF ground block. The center coax conductor indexes into a close tolerance tube that is resilient (spring) brass and is gold plated. The close center-tube tolerance assures a tight connection, the gold plating assures a good electrical connection and the overall performance is greatly improved over standard designs.
Internally, the center conductor tube is insulated from the inner skin of the barrel by a maximum air gap which results in much less RF loss. Insertion loss is extremely low.