The Brother CS7000X sewing machine uses SA156 plastic bobbins. These are 7/16″ in size, so you’ll want to make sure your thread is too! I had issues with generic bobbin fill before trying out these from the hobby lobby (it’s a real pain when they don’t work).
Luckily it wasn’t as big of an issue this time around because there were enough colors pre-spooled up for me right off the bat – saving lots of prep time and frustration