These are Kadee?« Centering Springs.

FEATURES: Precision engineered metal centering springs
Designed for use with Kadee?« #3, #5, #9, #10, #11, 20-Series,
40-Series, #58, #505, #506, #507 and #508 Couplers.
Very detailed instructions
Made in the USA

INCLUDES: (12) Centering Springs

SPECS: Scale: HO 1:87
Kadee
Part KAD634