authentic originals produced by Chicago's Harry Davies Molding Co., not a repro! Often called a "stove"-style knob, with raised center grip. 

 stamped with the Daka-Ware branding and patent around the bottom rim of the piece. 

These are from a surplus stock we purchased around 2017 - they could be anywhere from 25-50 years old. They certainly seem '80s or back to me, with somewhat of a resinous Bakelite character. 

Style
Cylindrical
Type
Smooth
Shaft Size
0.250" (6.35mm)
Diameter
1.130" (28.70mm)
Height
0.560" (14.22mm)
Indicator
Line on Top and Side
Material
Phenolic
Color
Black