※Huanyu Thank you for your favor and trust to choose our product ! ※Features: Cell batteries High accuracy to 0.5mm Cornea reflection coincidence system ensures simple, fast and accurate measurement. Single and both eyes measurement are selectable. Compensation knob allows better observation for examiner when necessary. ※Specifications: 1.Range of measurement: ⧫45~82mm(total) in 0.5mm steps, ⧫22.5~41mm(each) in 0.5mm steps. 2.Focus Range: 30cm to infinity. 3.Power Supply: AA Battery *2 4.Dimensions:230x170x62mm ※Note To ensure after-sales service, please confirm that the seller of the order product is "Huanyu". ※About Shipment: After your order is confirmed, the product usually takes about 5-10 business days to arrive to your hand. Please pay attention to the Emails from Amazon after placing the order. If there is any questions, welcome to contact us.