It's a 3d printable version of the orriginal ultimaker head. It fit's on the wooden parts. *Note: This head is 1cm longer than the orriginal wooden one! I mand this because my fan was touching the sliding blocks. Using this head will reduce the print height with 1cm. Make sure to print this with a large brim or it will easily get detached. It is designed in such way that it wont need any support.