This set of prints includes a working tow pin to complete a model tug boat. It is modeled in 1:200 scale.
Tow pins are used to improve deck security on a tug boat and guide the towing ropes / chains; many kinds can be retracted to "disappear" under the deck, see e.g. https://youtu.be/5fDFRQLGsiM
(external link, no affiliation with Micro Boat Hobby or Shapeways).
The tow pins in this model are operated all as one (4 tow pins) by a single servo, best operated with a 0.5mm steel wire (see video below). No additional parts are needed, although a servo and the steel wire is not included with this set of prints. The part is recommended for experienced modelers only. It can be painted.
base plate approx. 29 x 13mm
space needed under deck: 14mm
pins come out by approx. 4mm