0640 Watch Mainspring 1.35 x 0.135 x 292 (11 1/2")(Calibers in description)

Dimensions:  1.35 x 0.135 x 292 (11 1/2")

End Type: T End

Material: Swiss Made unbreakable

Calibers: 

Hamilton mainspring number 2321, Hamilton mainspring number 2521, Hamilton mainspring number 718201, Hamilton 986A, Hamilton 987, Hamilton 987A, Hamilton 987E, Hamilton 987F, Hamilton 987S