The red buttons are hydro line caps, the sort the come on the fittings of all F-15 hydro parts from either the manufacturer or depot to keep hydro fluid in or f.o.d. out of lines and components as they are shipped to wherever they need to go. Back before I came to hate Star Wars, when I was working on my own lightsabers I found and "appropriated" handfuls of those caps from the hydroshop at the base I'm stationed at.
John