Scheneider Silver Ballpoint : for leather, vinyl and rubber.

This ballpoint writes an opaque silver ballpoint line and works well on both
light and dark paper. It also marks vinyl, leather and rubber and will wipe
off non-porous surfaces.
This has led to much use in the craft and professional market for marking up
non-porous surfaces and textiles before cutting - traces can then be
wiped off.
Medium point, approx 0.4mm line.