Description: This adapter ring is suitable for M42 lens to Pentax PK camera. The high precision lens mount of this ring is compatible with the PK camera. And the smooth interface will not only protect your camera and lens, but also ensure the safety and solidity of the lens transfer. Features: Smooth Interface & Compatible Thread: This adapter ring adopts a high precision lens mount which makes it accurately compatible with connecting M42 lens to a Pentax PK camera. The interface is so smooth that it will protect the camera and lens, and make lens transfer firm. Fitment: It is suitable for M42 lens to Pentax PK camera. The aluminium alloy material makes fit very smooth without stuck. Durable & Wearable Ring: We manufacture this step-up ring with aluminium alloy and then apply an advanced craftsmanship, which withstands corrosion and other abrasive elements that often encountered in outdoor photography. Cause No Damage: It will fit perfectly and cause no damage to your lens or camera, which is very reliable and practical. Extremely solid and lightweight: Specifically designed for your camera for a tight and secure fit. No wobbling or cross-threading. Specifications: With this third-party adapter, you can realize: M42 Screwed Mount Lens installed on Pentax K Mount Camera Material: Aluminium Alloy Color: Black Advice to use: 1. With some ring adapters,you have to Turn on 'shoot without lens' to use MF lenses with it. 2. Some Lens can mount, but be careful with retractable lenses whose have protruding rear elements that can come into contact with the mirror of full frame DSLR cameras and damage the camera.This has nothing to do with the design of this adapter. It is a recognised feature of certain lenses and cannot be overcome simply by using a different adapter. 3. Although the lens will fit physically, automatic diaphragm, auto-focusing, or any other functions will not operate correctly while using this adapter.In this case "stop-down mode" will need to be used when metering since the lens does not have the ability to have its aperture controlled by the camera body. You can shoot with manual mode or aperture priority mode. 6. For some "AF" adapter, it is didn't mean you can use Auto focus, it only have an indication (bee sound) when you manual focal length actually. Package List: 1 * M42-PK Lens Adapter Ring.