1.replacement for X1 ( V2, V3, V4 but not for V1) 3D printer 2.Easy to exchange: Just pull out the ribbon cable, undo 3 bolts, remove one head, replace it with another, 3 bolts back on, ribbon cable back in it's slot, re-level 3 It is a complete upgraded hot end for the X1, it's all there with a quilting motor, thermistor, heater , circuit board, LED circuit board, complete hotend and heating sock. 4.Direct drive extruder, great support for flexible filament. 5 The PCB on V1 is a little bit different, so it does not compatible with that version, V2, V3, V4 all are OK, please to purchase. Colour:Photo Color Material:plastic Package Contents: 1 x Extruder Kit Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.