This little 18x18mm section is quite different from the wide boards elsewhere in the range. It’s square, compact and useful for the sorts of jobs where a standard piece of moulding would simply be too much timber. You might need it to finish an edge, tidy up a small gap or replace a similar piece that’s seen better days. With the same measurement on both sides, there’s no wide face or narrow face to worry about either. It’s dressed pine, so the timber itself will have some natural variation. Keep an offcut if you’re doing repeat work; it’ll make matching later jobs much easier.