As any experienced guitarist will know, the high E string is the most likely string to snap (at the most inconvenient time possible, usually). It's always advisable to have a spare stash of high E strings for when this happens.
These strings are sized as 0.009 inches (9 gauge), 0.010 inches (10 gauge), or 0.011 inches (11 gauge).
Please note the 11s are in packets labelled 2nd - they can be used as Bs in thinner gauge string sets.
Please note they are not long enough for Bigsby equipped guitars.