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06MFS-04MFS STRAIGHT

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Description & Features

A straight hydraulic adapter from Brennan Industries, this fitting connects a 3/8 inch male flareless seat (06MFS) end to a 1/4 inch male flareless seat (04MFS) end, making it suitable for reducing between two different line sizes in a single inline connection. The 06MFS-04MFS Straight carries an 11/16-16 thread on the larger end and a 9/16-18 thread on the smaller end, with corresponding drill sizes of 0.264 and 0.172 inches respectively.

With an overall face-to-face length of 1.17 inches and a 0.750 inch hex, the fitting is compact and straightforward to install with standard tooling. It is part of Brennan's FS2403 series and is well suited for hydraulic line assemblies where a straight-through, cross-size flareless connection is required.

SKU: FS2403-06-04

Supplier Part Number (MPN): FS2403-06-04

Alternate Part Numbers: AFF2000T0604S, C1ED19, FF2403-06-04

Specifications

Brand
BRENNAN
a1 Drill Dimensions
0.264 in
a2 Drill Dimensions
0.172 in
Connection Size 1
3/8 in
Connection Size 2
1/4 in
Connection Type
Male ORFS
Connection Type 1
Male SAE ORFS
Connection Type 2
Male SAE ORFS
Dimension Standards
SAE J1453, SAE J515
Dimensions
1.17 in L
Finish
Trivalent Zinc-Plated
Fitting Type
Adapter
Hex Size
3/4 in
Material
Steel
Material Construction
AISI 12L14/1045 Steel
Operating Temperature
-40 to 250 deg F
Series
FS2403 Series
Thread Size
11/16-16, 9/16-18
Tube OD
1/4 in
Tube Outside Diameter
1/4 in

Product Questions & Answers (3)

Question by: Lynn H on Jul 18, 2025, 2:47 PM
trying to step down from a 3/8 line to a 1/4 line, is this the right straight adapter for that?
Answer by: Customer Support on Jul 20, 2025, 6:58 AM
For reducing in a straight run, it connects a 3/8 inch male flareless seat end (06MFS) to a 1/4 inch male flareless seat end (04MFS), so it is meant for that 3/8 to 1/4 step-down in one inline fitting.
Question by: Donna H on Apr 3, 2026, 11:34 AM
trying to reduce from 3/8 line down to 1/4 in a tight spot, will this fitting work inline without needing extra adapters or couplings?
Answer by: Customer Support on Apr 5, 2026, 10:38 AM
For a straight inline reduction between a 3/8 flareless seat and a 1/4 flareless seat, this is exactly the fitting for that job. The larger end threads at 11/16-16 and the smaller end at 9/16-18, so it handles both connections in a single piece. At 1.17 inches face-to-face, it keeps things compact, and the 0.750 inch hex means you can torque it down with standard wrenches without any trouble.
Question by: Terry E on Aug 13, 2025, 8:39 AM
So this fitting goes from 3/8 to 1/4? Just want to make sure I'm reading it right.
Answer by: Customer Support on Aug 14, 2025, 11:00 AM
That's correct. This straight adapter connects a 3/8-inch male flareless seat to a 1/4-inch male flareless seat.

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