Round assembly that applies tension to the bobbin thread and holds the bobbin in the machine. The latch mechanism locks the bobbin case into the hook. It is important that the embroidery machine operator be trained to properly install the bobbin case in the machine to minimize costly repairs of the machine. After the bobbin case in properly positioned to the bobbin case holder in the hook, it should then snap on the spindle when it is fully loaded. Most embroidery machines use an “L” size bobbin and bobbin case; even though sometimes larger hook styles are used.