Four-way stretch

Two-way stretch gives along one axis only, typically across the body. Four-way gives both across and along, which means it follows a joint through its full range instead of restricting it at the extreme.

On a sun glove that is the difference between something you can tie a knot in and something that bunches at the knuckles and comes off. On a shirt it means a full casting stroke does not pull the hem out.

Recovery matters as much as stretch. Cheap spandex blends stretch once and stay stretched, so the glove that fit in April is loose by July.

Stretching a fabric also opens its weave, which lowers the UPF it delivers. A four-way stretch sun glove pulled tight over a large hand is protecting less than the label claims, which is another argument against sizing down.