Plastic bobbins for use with Schacht boat shuttles. These bobbins have specially designed ends for trouble-free release of yarn.
 
Sold in pairs, sizes to fit Schacht shuttles as follows:
4"/10cm bobbins for 9"/23cm mini open-bottom boat shuttle, 11"/28cm shuttles and the double-bobbin shuttles
5"/12.5cm bobbins for 13"/33cm shuttles
6"/15cm bobbins for 15"/38cm shuttles