The center slot, front arc groove and rear arc groove for the edge of the half frame or frameless eyeglass lens. Detailed product description: 1 、 LY-1800C adopts copper panel, AC motor, fine blade; 2, suitable for all kinds of glass, resin and PC lenses; 3, groove depth, position adjustment (front - middle - back); 4, adjustable groove depth: from 0 to 0.3 '' (0 to 0.7cm); 5, the width of the slot: 0.3 '' (0.65cm), suitable for various sizes of lenses and narrow long lens slot; 6, lens thickness: from 0.1 '' to 0.4 '' (1.5 to 11mm); 7, lens diameter: from 7.1 '' to 27.6 '' (18 to 70cm). Parameter: Voltage: 110V/60Hz Power: 80W Net weight:6.4lbs (2.9kg) Inner box size: 10.6 '' * 9.1 '' * 8.7 '' (27 (L) *23 (W) *22 (H) cm)