Early US cymbal arms were generally 5/16" diameter. Shown is a modular cymbal seat that sits freely on the L-arm section.
Gretsch
Gretsch 8657 removable cymbal seat, 1940s-50s.
For use with modular cymbal arms and stands, intended to be left on the cymbal after tear down. Probably made by Walberg & Auge. Unthreaded on bottom, top threads are 5/16-24.
Gretsch round badge cymbal arm, 1950s-60s. Produced by Walberg & Auge, but sold only under the Gretsch name.
The tilter design is likely the last instance of this primitive Walberg & Auge ratchet tooth style, used in earlier decades on tom mounts.
Ludwig
Ludwig & Ludwig hoop-mounted cymbal arm, 1920s-30s. A primitive hanging design from the traps era.
L&L may have purchased these from Walberg & Auge, or they may have made them in house.
The first style of Ludwig cymbal arm after they stopped purchasing arms from Walberg & Auge. Transition period, late 1950s-early 60s.
Note slightly different tilter shape. Early knurling on Ludwig arms was diamond-shaped as well, until about 1965.
Ludwig cymbal arm. 3/8" diameter, the knurling probably indicates a late 60s or 70s model shown.
The L1372 is a modern reissue version of this part that is nearly identical to the originals.
Rogers
Rogers Swivomatic cymbal tilter, 1960s-70s
This is a modular version, affixed with a key bolt onto a 1/4" post; Rogers also made fixed tilters for stands in the 1970s.
Slingerland
Slingerland cymbal tilter, 1960s
The late 60s-70s version of the same tilter was chrome rather than matte gray.
Sonor
Sonor 60s cymbal tilter, 1960s-70s
All 6mm threads. Sonor used threaded discs rather than wing nuts.
Trixon
Trixon cymbal tilter, 1960s
Walberg & Auge
Walberg & Auge cymbal arm, "skeleton" style tilter section. Sold under all the US major brands' names in the swing era.
A later hybrid version of the same style
Walberg & Auge cymbal arm tilter, 1950s. Sold under other US brand names.