Prym's clear plastic bobbins are ideal for Singer sewing machines with the special Apollo bobbin holder. With a diameter of 20mm and a height of 10.5mm, these bobbins are inserted horizontally into the sewing machine from above and do not require an additional bobbin case. The resistant plastic ensures greater durability and a clear view of the color and the amount of thread remaining. When choosing a spool holder, it is important to consider the material to prevent rapid wear. Avoid sudden lower thread runout and maintain the efficiency of your sewing machine with these high-quality bobbins from Prym.