Ophthalmic Optical Optometry Trial Frame metal,PD adjustable PD Scale:50mm~80mm Net weight:61g Knobs fastened with screws Back lens holders of round corners Easily-shaped ear rests Available for 3 pieces front , backside 1pcs  trial lensed to be inserted at each side. PD scale 50mm~80mm Net weight 61g Feature 1 Knobs fastened with screws Feature 2 Back lens holders of round corners Feature 3 Easily-shaped ear rests Feature 4 Available for 5 pieces trial lenses to be inserted at each side Package Individual Box