Comprising two metal disc, each 75mm with variable separation, supported on insulating pillars and provided with insulating handles on the ends of the adjustment slide rods, 4mm sockets are drilled in the end of the adjustment rod. A rectangular glass plate is supplied which mounts in clips between the two disc and may be easily replaced by a mounted on a polished wooden base.

Comprising two metal disc, each 75mm with variable separation, supported on insulating pillars and provided with insulating handles on the ends of the adjustment slide rods, 4mm sockets are drilled in the end of the adjustment rod. A rectangular glass plate is supplied which mounts in clips between the two disc and may be easily replaced by a mounted on a polished wooden base.