Threaded rods (studs) are for SI tapped CF flanges. Applications include:connect double-sided flanges; make bolts “emerge’’ from blind-tapped flanges, and mount protective plastic covers over glass viewports. Plate nuts are for clearance (through-hole) CF flanges. They are metal plates with 2-threaded holes, shaped to match the corresponding CF flange's bolt hole patterns and replace the individual nuts. The plate nut’s major advantage is, once two bolts are manually started, the plate nut acts as its own backing wrench and washer—the bolts are tightened using one wrench.