This adapter connects a 1" G (BSPP) female thread to a 1 1/4" NPT male thread, so you can join two different plumbing standards without replacing existing pipework. It's built from lead-free brass and ships with a washer, since G (BSPP) threads are parallel and seal with a washer rather than tape or sealant.
What It Connects
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Female side: 1" G (BSPP) — parallel thread
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Male side: 1 1/4" NPT — tapered thread
Key Features
- Lead-free brass construction, safe for potable water
- Washer included for a proper seal on the G thread side
- Simple screw-in installation, no special tools required
Common Uses
- Shower systems and larger-diameter supply line connections
- Hose-to-fixture adapters
- Fixture retrofits where thread types don't match
Specifications
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SKU: CSSL56160960
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Material: Lead-Free Brass
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Finish: Brass
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Female Thread: 1" G (BSPP)
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Male Thread: 1 1/4" NPT
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Overall Length: 1 3/8" (38mm)
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Male Thread Diameter: 1 1/4" (Ø34mm)
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Male Thread Length: 5/8" (18mm)
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Hex Size (Female End): 1 3/4" (45mm)
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Installation Method: Screw-In
Package Includes
- 1 x Adapter, 1" G Female to 1 1/4" NPT Male
- 1 x Washer
Installation Notes
- Confirm your existing fittings match: 1" G female on one side, 1 1/4" NPT male on the other.
- Seat the included washer on the G thread side before threading — this is what creates the seal.
- Hand-tighten first, then snug with a 1 3/4" wrench. Don't overtighten.
- Plumber's tape can be used on the NPT male side if needed.
- Run water briefly and check the joint before finishing the install.
FAQ
Q) What's the difference between G thread and NPT thread?
G thread (BSPP) is parallel and seals with a washer. NPT is tapered and seals by compression. This adapter connects the two.
Q) Do I need plumber's tape?
The G thread side seals with the included washer. Tape is optional on the NPT male side.
Q) Is this safe for drinking water?
Yes, it's lead-free brass, rated for potable water use.
Q) What size wrench do I need?
The hex measures 1 3/4" (45mm) across the flats.
Q) Will this fit my shower system?
If your shower system uses a 1" G female connection and needs to connect to 1 1/4" NPT, yes.
Q) Is this the same as the 3/4" NPT version?
No — this adapter's male end is 1 1/4" NPT, a larger thread than the 3/4" NPT version. Check your existing fitting size before ordering.
