Needs a M6x75mm or ¼' x 3' screw and nut.
Will slide into the tube of the Urban Arrow Family and will clamp from the inside when the screw is tightened
It is intimidating a seat post. Anything designed to be mounted on a seatpost can be mounted with this print.
Source file is on Onshape:
https://cad.onshape.com/documents/7a970dd6656f1f60bcd06fa2/w/02cc7f2df20f44c5e7519f53/e/ea9294982b55b66813b73e7d
The author marked this model as their own original creation.