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Brass Compression Fitting For Plastic, Copper, & Aluminum Tubing, 0.25 Inch Tube OD To 1/4-18 Female NPT, Straight

Brand Danfoss Power Solutions (II LLC Aeroquip)	Brand Aeroquip	Pack Size 1.00	UOM EA	L 1.03	Supplier Part Number 66X4X4	Thread 1 1/4-18	Tube O.D. 0.25	Tube O.D. 0.25	Alternate Part Numbers Alternate Part Number C1HQ98, Alternate Part Number MI-00334026, Alternate Part Number MINO-00925F73353	Product Weight 0.07 lbs

Product Questions & Answers 3

Product Questions & Answers

What kind of tubing can I use with this fitting?

Question by: Larry G on Feb 26, 2026, 7:07 PM

It's designed to work with aluminum, copper, and plastic tubing. Keep in mind that plastic tubing, except for Eaton PT230, needs the 2030 insert. It's not recommended for steel tubing, though.

Answer by: Customer Support on Feb 28, 2026, 7:56 AM

got some 1/4 inch OD copper tubing on an old pneumatic line i need to tie into, will this fitting work for that hookup?

Question by: Lyle Y on Mar 12, 2026, 12:43 PM

Copper tubing with a 1/4 inch outer diameter is exactly what this fitting is built around. The female NPT thread on the other end is 1/4-18, so as long as your mating port matches that thread size, you're good to go. No flaring needed either, which makes the job a lot cleaner.

Answer by: Customer Support on Mar 13, 2026, 3:36 PM

got a 1/4 inch tube line, will this fitting screw into a standard 1/4 npt port?

Question by: Terry W on Mar 25, 2025, 10:27 AM

It is made for 0.25 inch tube OD on the compression side and a 1/4-18 female NPT thread on the other end, straight configuration. That means it threads onto a 1/4-18 male NPT connection and grips the 1/4 inch tubing without needing to flare the tube.

Answer by: Customer Support on Mar 27, 2025, 9:54 AM

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Model Number	Tube O.D.	Thread 1	L
66X4X4	0.25	1/4-18	1.03
66X2	0.125	1/8-27	0.75
66X3	0.1875	1/8-27	0.78
66X4	0.25	1/8-27	0.78
66X6	0.375	1/4-18	1.06
66X8	0.5	3/8-18	1.12