Buying the three pieces separately usually means three different fits.
These sets are matched: the case, the keyboard cover and the screen
protector are cut for the same machine and sized to work together.

One thing worth knowing before you buy any keyboard cover, ours
included. On the thin M-series Air, the gap between screen and keyboard
is measured in fractions of a millimetre. A cover that's too thick will
press into the display every time the lid closes, and we see the result
of that often enough to mention it. Ours are cut thin for this reason,
which is also why they feel less substantial in the hand than some
alternatives. That's deliberate.

Choose your exact model — check the A-number on the base of your
MacBook rather than the screen size, since "13-inch" has described
several different bodies since 2020.