Are all M bobbins online the same?

[SewingDiva]

I went online to purchase M bobbins for my Millie. They are much more reasonably priced than from my dealer. They look the same. Will they fit my machine? I have tried to locate specs for the bobbin and can’t find any in my info. My bobbins are flat on the sides. It’s hard to tell by the pics online for what I want to purchase but they may be slightly curved on the sides. Has anyone purchased from Amazon or anywhere else? 

[jimerickson]

They are not all the same.  They all will probably fit and work in your machine, but the quality control on their respective manufacture aren't the same.  The black ones (probably the least expensive) are the poorest.  I've thrown away about one in ten, and no longer buy them.  The  bronze colored ones are good, but I really prefer the extruded aluminum ones.  I figure the manufacturing tolerances are probably the tightest on them.  None of these need be expensive.  I paid about $1.00ea for the black, about $2.50ea for the bronze colored, and about $1.50ea (I think-can't really remember) for the aluminum ones.  These were bought in ten plus lots, no one at a time.  If you're paying a lot more than that per bobbin, you can probably do better on line.  Jim 

BTW, the aluminum ones I've bought where plain silver, not the colored anodized ones, which I think are a little more expensive.