Faucet aerators with flow restriction
In this simple application, the flow is limited through the size of the flow bore so that it precisely corresponds to a set value for a certain pressure range (e.g., 3 bar / 43.5 psi).
Neoperl refers to the products used for this as "flow restrictors". Flow restrictors have a low flow rate at low pressure, while at high pressure the flow rate is often higher than necessary.