This is a Swagelok Swage DV-1 stainless steel supplied part for distilling. The DV-1 is a ball and needle 3/8 valve kit. A high vacuum rated for up to 8/9 scale. This item itself is a major tool in controlling vacuum or bleeding atmosphere into pump without risking any leak point. Swagelok is leading the industry in these types of valves. See for yourself: swagelok/valves
Summit also offers a 2 piece valve setup in the Swage DV-2
No longer offered in 1/4 inch fitting, all valves are now 3/8.