Review on Simthread 25pcs 90WT Prewound Bobbin Thread Set: Size A Class 15 (SA156) with Storage Case - White, 60S/2 - Perfect for Brother Embroidery and Sewing Machines! by Morgan Gilmore

I have a set of Simthread embroidery threads that I find very valuable. Unfortunately, pre-wound plastic Class 15 (90 weight) spools do NOT have the same dimensions as Janome spools, although both are classified as 'Class 15'. My Janome 350e bobbin area started rattling at high speed and I couldn't figure out why (I clean under the needle plate and change needles frequently and use Madiera, Floriani and Simthread embroidery threads) until I finally compared and found the two that the Simethread spool is shorter than my Janome brand spool. In the picture, the Janome coil is on the right (with the letter "J" on the core) and the Simthread coil is on the left (has a slight blue-gray tint). Be careful when you have Janome.