The gas struts are an option on all Millturn machines from 2015 and 2016. Thety are standard on 2017 models. The gas struts counter balance the weight of the mill head so the speeds both up and down are equalized and increased. The set comes complete with 2 struts and mounting hardware. You will only need to drill and tap some holes with 8MM X 1.25 tap. This kit can also work on Patriot VFD machines from 2010 to 2014 for those wishing to use the A axis for longer milling travel.