1、Aluminum Alloy shell is precision machined, stable and durable for long time use 2、This is a 4X achromatic objective lens for biological microscope 3、It can eliminate unwanted reflections and increase contrast 4、Offers observation without additional chromatic aberration, make image more clear 5、The Length of the objective lens is 30.5mm, easy to use Features: 1. Aluminum Alloy shell is precision machined, stable and durable for long time use. 2. This is a 4X achromatic objective lens for biological microscope. 3. It can eliminate unwanted reflections and increase contrast. 4. Offers observation without additional chromatic aberration, make image more clear. 5. The Length of the objective lens is 30.5mm, easy to use. Specification: Item Type: Achromatic Objectives Lens Material: Aluminum Alloy + Optical Lens Color: As Pictures Show Magnification: 4X Tube Length: 160mm / 6.3inch Conjugate Distance: 185 Cover-glass Thickness: 0.17mm Objective Lens Length: 30.5mm Mounting Size: 20mm（Standard RMS Thread) Item Size: 5 * 5 * 5cm / 2.0 * 2.0 * 2.0inch Package Weight: Approx. 41g Package List: 1 * Achromatic Objectives Lens Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.