What regulator means in practice
A scuba regulator reduces cylinder pressure in stages so breathing gas can be supplied to the diver. The term can mean the complete assembly or, informally, the mouthpiece component. Be specific when discussing rental equipment, faults or servicing.
An example to think through
A booking includes a “regulator set”. Ask the provider which components are included and how the configuration will be explained during the equipment briefing. Write the actual model names in your equipment record instead of only the brand.
A common misunderstanding
The regulator delivers the supplied gas; it does not identify the mixture for you.
Underlying concept: PADI — Regulator. The example is an original YouDive study prompt, not a reported dive.