There is a 10-rated used Really Right Stuff BH-55 Ball Head with Full-Size Lever-Release Clamp
in stock at
This is an outstanding ball head in like-new condition with a nicely-reduced price.
Also check out the nice selection of used
RRS L-plates for popular camera models,
including for cameras using the VG-C4EM (a7R III, a7R IV, a1, etc. and VG-C3EM, for the D850, etc.).