Difference between class 15 and 15J bobbins
 

Can anybody explain what the difference is between these two bobbins class 15 and class 15J? The only thing I have come up with so far is price. Thanks in advance --- and an extra special thanks to those who take the time to post pictures. I really enjoy all the daily eye candy.

here's a good explanation on a previous thread here on the QB http://www.quiltingboard.com/main-f1...ml#post3010947

My machine uses the 15j. I bought some on Ebay....the hole in the center would not fit on the spoke? to wind them. I then order some from Sew vac usa on Ebay and they were perfect. I am not associated with sew vac usa but their prices are good and they ship fast. I highly recommend them.