Half of baby grooming is getting a dried booger out of a nose without turning the whole thing into an event.
What it is for: Dried nasal debris, visible wax at the outer ear, and the dirt that packs in under a fingernail. What it is not for is a blocked, running, actively congested nose. That is what a nasal aspirator does, and the two tools solve different problems. If your baby is snuffly and struggling to feed, reach for the aspirator; if there is a dried crust sitting at the edge of a nostril, reach for this.
The four tips: A nose tip for dried debris. An ear tip for wax you can already see at the outer ear. A nail tip for cleaning under and around the nail edge. And a fourth marked everywhere else, the general-purpose one for the bits that are not a nose, an ear or a nail.
How far it goes in: Each tip is shaped with a stopper, a widened section behind the working end that keeps the tip from traveling further in than it is meant to. Even with that, treat this as a tool for what you can see. Do not push a tip into the ear canal or up past the visible part of a nostril. Wax deeper in the canal is a conversation with your pediatrician, not a job for a pick.
Care, starting with what not to do: Do not microwave it, do not boil it and do not put it in a steam sterilizer bag. It is top-rack dishwasher safe. Otherwise wash it in warm soapy water, rinse, and let it air-dry fully before it goes back in the drawer.
Getting started: Check the pack for the age guidance, and ask your pediatrician if you are unsure about your baby. Pick a calm moment with good light, keep the head still, and stop the moment your baby starts twisting away.