Manual Vacuum lens blocker (alloy free). Device allows continuous and automatic locking of the lenses on special lens-holder supports through the only action of the vacuum. The versatility and ease of use of the VACUUM SYSTEM offers considerable advantages compared to alloy blocking in every aspect of lens mass-production: Reduced dedicated man-power thanks to practice and faster operations. No protection film or paint to applied on the lenses before the blocking. Reduced number of lens-holder thanks to faster lens blocking and unlocking. Irrelevant operating costs. Greater blocking force. Best advised for lens mass-productions of mineral glass.