Three-layer Card Slot: The three optometry lenses can be placed at the same time, directly clamped on the flat glasses, and the angle can be adjusted manually. Comfortable to Wear: The silicone glasses temple cover is made of ABS material, which is comfortable to wear and can protect lens to reduce wear. Clear Scale: The axial position is accurate and the scale of the optical test frame is clear. Better Observation: Horizontal single eye test frame for better observation of scattered position. Suitable Places: The optical test frame is suitable for optometry in ophthalmic optical shops, etc. 2X Adjustable Trial Lens Frame Clip for Optometry in Ophthalmic Optical Shops Comfortable to Wear Single Eye Test 2Pcs Trial Frame Clip Lens Frames Optometry Single Eye Optical Test Frame Testing Accessories Glasses Equipment Stand Name: Single Eye Trial Frame Scale: 0-165 Card slot: three layers Colour:Black Material:ABS Specification: A Package Contents: 2 x Monocular optical test frame(With balance instrument) Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.