Only 0.311", although because there is so much overlap in what is considered the "centre and fringes" of what constitutes stabilization, it would also be useful for 0.308". You can forget it for 45 cal!
Remeber that just because the simple table or complex calculations (whatever you prefer) state that you require a 1:10.36" twist does not mean that a 1:10.37, 1:11 or even 1:12 will not stabilize the bullet, but you should not expect that a 1:14 will.
