This is a compatible lens I replaced when the lens on my Panasonic VL-VH573 doorphone became unclear. I keep it in stock in case it breaks. I have received reports from buyers that it could also be installed on the VL-VH556. I have not been able to confirm this, so please purchase at your own discretion if you wish to try. 1/4" M12 Mount 1.05mm Focal Length Fisheye Lens I replaced it from the original, and the angle widened, resulting in a clearer image. I believe it has an IR cut filter (infrared cut filter): This is a filter that transmits visible light and blocks infrared light. It is used to prevent unwanted infrared light from entering the image sensor of a digital camera and to capture color images with hues similar to those seen by the human eye. Please refer to information on YouTube and other sites regarding replacement for the VL-V571. My process was: ・Remove the doorphone screws. ・Remove the lens connector screws (there were three). ・Remove the old lens using pliers or other tools (be careful as it may be stuck or fragile). Use the existing base. The base cannot be used because the screw positions are different. Please use at your own discretion. ・Attach the new lens (just screw it in). ・Adjust the focus. This is the most difficult and time-consuming part. I connected the wiring (about 2m of doorphone wiring purchased separately) to the child unit 2 on the back of the monitor and adjusted the focus indoors. The entire process took about an hour. Please purchase only if you are comfortable with DIY. The lens becomes unclear periodically, so it's good to know how to replace it cheaply. Please be aware that the view will be different from the original. Please refrain from purchasing if you are overly concerned about details. I do not offer discounts.