I removed these screws from a lot of Herman Miller stacking fiberglass shell chairs that I purchased at a university surplus auction 20 years ago. 
Eames Herman Miller SET OF 4 angled rubber boot glides LCM DCM DSS DAX
Set of 4 Genuine Vintage Herman Miller Eames Bikini Covers for Wire Chair
Eames Herman Miller Aluminum Group Desk Chair Replacement Armrests Set of 2
Eames Herman Miller Aluminum Group Desk Chair Replacement Arm Casting Set of 2
Set of 4 VTG MCM Herman Miller George Nelson Chrome Credenza Desk Furniture Legs
Herman Miller Eames Glides For H-Base, Shell Chair Stacking Base. (Set of 4)
