"M" style large bobbins #18034, steel (nickel plated) with  knurled stem for quick winding for Seiko.  

Sold in pack of 5 pcs.    

Precision made in Taiwan.

Size:  25.4x10.8x6mm 

Fits Seiko models:  H-2B/2BL; LAH-1LC/1LC/N; HCL-2BL; LSC-8BL/8BV; LTW-27BL; LZH-EVL/EVLC; NCL-2BL; STH-3BL/6BL/7BL/8BL, etc.