This block is intended for use on early stock CR-10 hotends. This hotends are identified by having a threaded thermal tube which joins the heater block to the red heatsink. If you have two additional screws present, you have the later version of this block.
This replacement heater block clamps down and squeezes your heater cartridge. This is a much better solution to securing the heater cartridge, and transferring heat. The stock heater block uses a single set screw.
The stock block single screw, pressed the cartridge against the opposite wall. This block has a positive clamping force for a much better surface contact between heater cartridge and block.
Please note, this block is narrower than the stock block. We feel this is good thing.
Your stock block is 20 mm wide. This block, as per E3D's design, is 16 mm wide. The extra width is unnecessary. See the photos in this product description to see how it compares to the stock block. This heater block will accommodate all thermal tubes with M6 thread. Stock 30mm length tube, is recommended
This is for the heater block only. It does not include thermistor, heater cartridge, thermal tube, or hotend heatsink.