The Galena Century Radio (GCR) Crystal Detector Arm Structure – Kit provides the basis for a quality Crystal Detector. This is the same basic arm structure used on the GCR crystal radios and crystal detectors. The Crystal Detector Arm Structure – Kit contains; two (2) milled Brass Support Rods; two (2) milled Brass Ears; one (1) milled Brass Pivot Ball; one (1) Brass Threaded Rod; one (1) Brass Thumb Screw; one (1) Phosphor Bronze Cat’s Whisker; one (1) Spherical Knob; two (2) Brass Washers; and two (2) 8-32 x 1” Brass Screws.