
Different sizes for different flows and needs. The bigger they are usually the heavier the flow support. Meaning they can absorb more per product without leaking. They also have uses. Overnight which will usually be nicer to help with sleeping, so the angle you sleep in won’t cause leakage, flexi for the “on the go” person that doesn’t want a stiff pad in their undies while moving around. And liners for spotting and light flows
Tampons have different sizes because sometimes if there’s more blood (heavy flow) you need a larger one to soak it up. Smaller tampons are for lighter days because it’s not good to leave them in for a super long time so there’s no point using a big one if there’s not alot of blood.