Do not choose an aerator from outer diameter alone. Match thread location, exact notation and the faucet model.
Identify exposed or recessed construction
Check whether there is a metal housing or a recessed outlet insert. Recessed designs may require a dedicated key and different parts.
An aerator with raised threads around its outside is male-threaded; threads on its inner wall are female. The faucet connection mates with the opposite form. The left section shows a female faucet and male aerator; the right shows the reverse.
Housing and internal parts differ
Neoperl distinguishes housing, insert, washer and male/female threads. Converting a US thread diameter to millimetres does not make it a metric equivalent.
Pitch is the spacing between neighbouring thread ridges. Similar diameter does not establish matching pitch or thread system. Compare the complete original specification rather than inferring a new designation from a ruler measurement.
Record the replacement specification
Find the full faucet model and original part number. Diameter narrows candidates but cannot establish pitch or fit.
- Find the faucet’s full model and market; open the manufacturer’s official parts list or support page.
- Locate its aerator entry and record exact part code, male/female designation and full thread notation. Separate housing designs from recessed ones.
- For a Neoperl part, match the housing table’s thread notation with the appropriate insert, washer and key. Insert-only replacement also requires the existing housing’s correct size.
- Without an official code or specification, send visible outlet/old-part photos and full model to the manufacturer. Ask for the replacement code, thread specification and washer/key contents; postpone ordering until confirmed.
| Check | Record |
|---|---|
| Construction | Housing / recessed |
| Thread location | Replacement male / female |
| Model | Full faucet model |
| Specification | Official thread notation and part code |
| Components | Matching insert, washer and key |
Pause an uncertain order
Do not force unmatched parts. Ask the manufacturer about seized or recessed components; confirm the official part specification before ordering.
A worked example
Hypothetical comparison: an official parts list specifies male M18×1. Candidate A has that notation; B says female M18×1. Despite the same diameter and pitch notation, B has the wrong form. Select A only after insert/washer and model approval checks. With only a roughly 18 mm measurement and no parts list, neither is confirmed.
Official sources checked
Official sources checked on 12 October 2026. Apply the cited model and market conditions. Examples are hypothetical records, not hands-on tests.