I think it is a crock myself too but someone else mentioned that it may be a mettler number in which a 100 equals a 60
thanks

that is what I am using now with the demo machine that I am using while mine is being unjammed. I usually buy it when I catch a half price sale at handcocks or joanns, I bought several types of bobbin thread and prewound for my brother se270d,but the singer don't like the prewound, thanks

thanks, that make all the sense in the world. I have also emailed singer support and asked them

This works great on my Brother Innovis1500.
The bobbin holds more thread and the embroidery is much softer (for babies designs)because of less build up of thicker thread at the back of designs

singer reccomended a website www.allthreads.com where you can buy RA 80 wt bobbin thread. i still have not found any 100 wt. they did have to replace the endless bobbin assembly and i haven't had much trouble since. thanks

Yes Marji,
With the Elna XQ models and Singer XL models, when you are embroidering and your bobbin runs out, the machine automatically stops, the hoop moves over to the left side, the machine stitches out the last of the bobbin with gigantic stitches along the right edge of the hoop, it then refills the bobbin and starts embroidering again in the exact spot it left off.

The thread to refill the bobbin is extremely fine, but boy is it ever strong, it cut into my hand before I could break it.

Now you can use ordinary embroidery threads in the 'ordinary' bobbin, such as when embroidering FSL and cotton thread for plain sewing, but I would not recommend these for the Auto Bobbin.
The only threads I have had a problem with on my XQ2, have been Black and White Rayon threads of cheaper brands such as Dragon, Q & A. Otherwise the machine will stitch out anything.

I did an indentical FSL design, with Gold Metallic thread, that stitched out perfectly on my XQ2, yet played up no end on the Diamond.
So not all machines will work equally well with the same thread.
HnR, M