1) Do not have to wind the thread. 2) Do not have to get rid of thread that left from bobbin. 3) Needle will not break because bobbin is made by thread itself. 4) Number of changing bobbin is deceasing and production is increase.     Products Color size length Remarks Prewound Bobbin Thread White L sideless coreless 135m/roll 75D/2 100% polyester Black 135m/roll White sideless w/core 120m/roll Black 120m/roll White sided 120m/roll Black 120m/roll White M sideless coreless 240m/roll 75D/2 100% polyester (jumbo) sideless w/core 200m/roll L sided 120m/roll 70D/2 100% polyester special order