Niches / Faucet aerator sizes
Size / fit replacement
Faucet aerator sizes: Cache M24×1 vs Junior vs US 15/16″–27 / 55/64″–27
When the screen clogs, the stream sprays sideways, or the housing strips, you buy a replacement aerator — not a new faucet. Shoppers often order a “universal aerator” without measuring thread (male vs female, metric vs US), or buy a standard Cache insert when the spout needs Junior, or forget the Cache key. This page helps you tell hidden Cache / Caché (threads into the spout; needs a size-matched key) from housing-style (insert + chrome housing + washer), match M24×1 STD vs M21.5×1 Junior vs US Male 15/16″–27 / US Female 55/64″–27, then reorder Amazon-available kits.
As an Amazon Associate we may earn from qualifying purchases. Product links below are marked PENDING_ASSOCIATES until a Tracking ID is configured — names and search paths are honest; no invented affiliate tag.
Who needs this
- Homeowners whose faucet sprays sideways, dribbles, or runs slow after mineral buildup in the screen
- Anyone with a flush spout and no visible chrome housing — likely Cache / Caché (needs a key)
- DIYers replacing a cracked housing or stripped washer on a screw-on male/female aerator
- Delta (and similar) kitchen owners who bought STD M24×1 Cache when the spout needs Junior M21.5×1
- Anyone who ordered a “universal aerator” multipack that will not thread onto their spout
How to choose (measure, Cache vs housing, when to replace)
- Look at the spout tip. Flush insert with no chrome ring = likely Cache (hidden). Visible chrome housing you can unscrew by hand or with pliers (cloth wrap) = housing style.
- Measure the thread before you discard the old part. Outside diameter of the male thread (or inside of the female housing), and note male vs female. Write STD / Junior / TJ / TT if Cache branding or size marks are visible.
- Pick the family — Cache and housing are not interchangeable by “aerator” alone.
- Cache / Caché (hidden): external thread into spout; blue radial o-ring; size-matched key required. M24×1 STD (~quarter), M21.5×1 Junior (some Delta kitchen), M18.5×1 TJ, M16.5×1 TT. Amazon example path: Neoperl Cache with key ~B0078QQHEC-class (M24×1 1.5 gpm).
- Housing US Male 15/16″–27: common residential male housing; threads onto female spout tip.
- Housing US Female 55/64″–27: common residential female housing; spout has male tip.
- Metric housing Female M22×1 / Male M24×1: common on European / many brand lines — not the same as US 15/16″–27 even when diameter looks close.
- Clean first, then replace. Vinegar soak and backflush often clear a clogged screen. Replace when the screen is torn, the housing is stripped/cracked, or the o-ring no longer seals.
- Watch “universal” listings. Prefer titles that list M24×1, M21.5×1, 15/16″–27, or 55/64″–27 — and whether a Cache key is included. Ignore “fits most faucets” alone.
- Confirm Amazon listing crosses. Prefer Neoperl / OEM size charts or titles that state exact thread. PENDING_ASSOCIATES until a Tracking ID is configured.
Comparison criteria (what matters when shopping)
| Criterion | What to verify |
|---|---|
| Style | Cache / Caché (hidden, key required) vs housing (insert + chrome housing + washer). |
| Cache size | M24×1 STD vs M21.5×1 Junior vs M18.5×1 TJ vs M16.5×1 TT — not interchangeable; key must match size. |
| Housing thread | US Male 15/16″–27 vs US Female 55/64″–27 vs metric Female M22×1 / Male M24×1. |
| Male vs female | Male housing screws onto female spout tip; female housing receives male spout tip. Wrong gender = will not start. |
| Wrong-size traps | STD Cache into Junior spout; M24×1 housing vs 15/16″–27 (not interchangeable); universal multipack without measuring; missing Cache key. |
| Key / tools | Cache needs size-matched key (often blue for STD). Housing often hand-tight or cloth+pliers — avoid chewing chrome. |
| Replace cadence | Clean when flow slows; buy when screen tears, housing strips, or Cache o-ring fails to seal. |
Common product paths (examples only)
These show up often in U.S. shopping. Verify thread size against your spout before ordering.
| Product path | Notes |
|---|---|
| Neoperl Cache M24×1 STD with key | Hidden regular (~quarter); 1.5 gpm paths common. Amazon example ~B0078QQHEC-class. PENDING_ASSOCIATES. |
| Neoperl Cache Junior M21.5×1 with key | Some Delta kitchen and related spouts — not STD. Confirm Junior before ordering M24×1. |
| Cache TJ M18.5×1 / TT M16.5×1 | Smaller hidden sizes; need matching tiny keys. Do not substitute STD or Junior. |
| US Male 15/16″–27 housing aerators | Common residential male screw-on; multipacks and Neoperl housing kits on Amazon / big-box. PENDING_ASSOCIATES. |
| US Female 55/64″–27 housing aerators | Common residential female screw-on; confirm gender on the old housing. |
| Metric Female M22×1 / Male M24×1 housing | Metric housing families — M24×1 housing ≠ US 15/16″–27. |
| Wrong-size trap: “universal aerator” | Photos hide male/female and metric/US differences. Measure first. |
FAQ
Is Cache the same as a regular screw-on aerator?
No. Cache / Caché threads into the spout and sits flush (needs a key). Housing aerators use a visible chrome ring, insert, and washer you unscrew from outside.
Is M24×1 the same as 15/16″–27?
No. They can look similar in photos (~quarter-size), but the threads are different. Ordering one for a spout that needs the other is a classic return.
Why did my “universal aerator” not fit?
Universal packs mix genders and thread standards. Match male vs female and US vs metric (or Cache size) to the old part — not the listing photo alone.
Do I need a key for every aerator?
Only Cache / Caché (and some vandal-proof housings). Standard residential housing aerators usually come off by hand or with a cloth and pliers. Size-match the Cache key (STD vs Junior vs TJ/TT).
Can I just clean it instead of buying a new one?
Often yes — vinegar soak and backflush clear mineral clogging. Replace when the screen is torn, the housing is stripped or cracked, or the Cache o-ring no longer seals.
How is this different from shower filter cartridges?
Shower pages cover inline shower-head filter media. This page is for the small tip aerator on a sink faucet — a size/fit thread part, not a shower cartridge.
Starter list of real products, brands, and resources
Honest directory notes only — no star ratings, no “best of” claims, no traffic or revenue numbers. Links go to official or primary shopping / education pages. Prices and stock change; verify before buying.
Neoperl — Caché / aerator size charts
Official Cache sizes (M24×1 STD, M21.5×1 JR, M18.5×1 TJ, M16.5×1 TT) and housing thread families. Site: Neoperl Caché · Neoperl aerators with housing
Home Depot — Cache / housing aerator paths
Retail listings for Neoperl Cache with key and common US housing sizes — useful for thread wording. Site: Home Depot
Neoperl Cache M24×1 with key on Amazon (PENDING_ASSOCIATES)
Search paths for STD Cache (~quarter) kits that include a key. Confirm M24×1 — not Junior. Search: Amazon search: Neoperl Cache M24x1 key · Amazon search: Cache aerator with key 1.5 gpm
Cache Junior M21.5×1 on Amazon (PENDING_ASSOCIATES)
Junior hidden inserts for some Delta kitchen and related spouts — not STD M24×1. Search: Amazon search: Neoperl Cache Junior M21.5 · Amazon search: Delta Cache Junior aerator key
US 15/16″–27 / 55/64″–27 housing aerators on Amazon (PENDING_ASSOCIATES)
Male 15/16″–27 and Female 55/64″–27 screw-on housings — confirm gender; not Cache and not metric M24×1 alone. Search: Amazon search: aerator 15/16-27 male · Amazon search: aerator 55/64-27 female
Quick reorder checklist
- Decide Cache (flush / no chrome ring) vs housing (visible chrome)
- Measure thread OD / ID and note male vs female
- Cache: match M24×1 STD vs M21.5×1 Junior vs TJ / TT — and buy the matching key
- Housing: match US Male 15/16″–27 vs US Female 55/64″–27 vs metric M22×1 / M24×1
- Remember M24×1 ≠ 15/16″–27
- Skip “universal aerator” unless thread wording matches your old part
- Clean (vinegar / backflush) first; replace when screen torn or housing stripped