411 / | HD | EXPANDED, THREADED, DRIVEN, HEADED, TOOL-DEFORMED, OR LOCKED-THREADED FASTENER |
511 | DF | FASTENER SECURING ELEMENT {3} |
516 | DF | .~ Resilient metallic {3} |
520 | DF | .~.~ Sheet metal {5} |
525 | DF | .~.~.~ Having plural longitudinal slits {2} |
526 | .~.~.~.~ And slit coincident with element axis |