Zinc Block
The vibrato bridge block is the anchor point for both the strings and the adjustment springs in the rear cavity. Being the central point of the vibrato system it does have a tonal influence, and that tone will ultimately be different dependant on the material used to create the block.
Billet Steel, Aluminium, Brass, Titanium and Zinc have and are used for vibrato blocks and the debate about which is best will no doubt continue for years.
The Wilkinson perspective is that we predominately use billet steel and Zinc for both the tonal properties and also the qualities of machining; in the case of the VG300 and VS100N we utilise Zamak 3 (Zinc Alloy), this is also the preferred material of Tyler Guitars and James Tyler.