Depends on A) What kind of thread you use and B) what kind of machine you have. Most longarms have a larger bobbin, but I'm assuming you're talking about a DSM.
Bottom Line is a thread designed by Superior Threads specifically for use in the bobbin. It's a 60 wt thread, which means it's finer and thinner, and therefore you can fit more on a bobbin.
BTW - if you're curious about why/how threads get their "weight" measured, check out Superior's "Education" tab on their website. Very informative.