M4 Styli,4mm Ruby Sphere,L20 Tungsten Carbide Shaft 
Straight styli are designed to inspect simple features where direct, unobstructed contact with a measured surface is possible. 
Ruby is regarded as the industry standard for stylus tips. It is one of the hardest materials available and suitable for most applications. 
Ruby provides a long life without wearing of the surface from abrasive materials.
Not Original, Compatible with Renishaw A-5003-4794
Specification
Ball material:Ruby
Stem material:Tungsten Carbide
Ball dia. mm (in.):4.0 (0.16)
Length mm (in.):20.0 (0.79)
Stem dia. mm (in.):2.0 (0.08)
EWL mm (in.):8.5 (0.33)
Package:1pc