There are several models of bobbin winders. I got one when I purchased each of my floor looms; I have two. The first one has a smaller shaft, the second a larger one. Winding thread for my scarf the other day I discovered that the larger shaft was needed for winding a standard sized spool. I will have to check today to find out how many spools I have of each size. Additionally, a relatively heavy bucket comes in handy when taking a bobbin of thread off of a ball of yarn. Rather than trying to control the ball, when it is placed in a bucket it has nowhere to go. This is a good thing…when I was winding my warp the other day the thread came off of the cone and before I realized what what going on I had a real rat’s nest to untangle.