Find a comfortable enclosed-pocket fit
Check whether the model is intended for bare feet or permits suitable socks.

Check whether the model is intended for bare feet or permits suitable socks.
Check whether the fin is designed for bare feet or suitable fin socks.
Compare the overall fin length with your bag's internal dimensions, especially for travel.
Check whether the fin is designed for bare feet or suitable fin socks. Lycra and neoprene socks take up different amounts of space, so assess the pocket with the type you intend to use.
Use the model's size chart and fit guidance. Pocket width and shape can differ between brands even when their size labels look similar.
Compare the overall fin length with your bag's internal dimensions, especially for travel. A shorter fin is useful only when the foot pocket also fits comfortably.
Read the intended use and blade design on each product page. For a modular model, check compatible replacement blades and whether the listing supplies complete fins.