Sewing Machine Handwheel Cogged Teeth Gear Belt.  Made In Taiwan, Numbers On Belt 150XL 025, Fits Models:

Riccar RE571, RM540, RE581, RE591, 2950, 3300, 3400, 3500, 3600, R750, R650, R551, R572

Baby Lock BL3000, BL4000, BL5000