Features: Our sensors are optically isolated, so in for case of failure, you will not have the risk of burning the printer motherboard, which is different from the setting of diodes or resistors. Our sensors are photoelectrically isolated, so, unlike the diode or resistor settings, you don’for t have to risk burning the printer motherboard in the event of a failure. Suitable for all printing surfaces, glass, aluminum substrates and removable architectural surfaces. The sensor is already connected to the optical isolation module, you only need to connect 2 wires and replace the Z-min connector.Including an icsp programmer for burning firmware. brand new and high quality The ABL kit is only a complete automatic bed leveling kit for the Pro 3D printer. Specifications: Product Name: Hot Bed Automatic Leveling Sensor Kit Function: Automatic Leveling Applicable Models: for PRO Colour: As shown Material: ABS+Metal U Disk Content: Firmware, Burning Software, Installation and Use Instructions, Drivers, etc. Package Includes: 1 Set x Hot Bed Automatic Leveling Sensor Kit note: Due to the different monitor and light effect, the actual color of the item might be slightly different from the color showed on the pictures. Thank you! Please allow 1-2cm measuring deviation due to manual measurement.