UNO O-Ring Boss Male Countersunk Blanking Plug

A UNO plug with an internal hex head that sits flush in the port. The neat way to blank a UNO port on a crowded valve bank.

Brand: Ayrtec – mild steel body with a plated finish, manufactured to the standards listed below.

Watch: Why You Need JIC Plugs Caps & O Ring Kit When Doing Hydraulic Repairs

Thread Standards

• SAE O-Ring Boss Male (UNO/UNF) – SAE J1926 / ISO 11926 straight thread O-ring boss. It seals on an O-ring squeezed against the port spotface, not on the thread.

How to Choose

• A plug is male and blocks a female port. A cap is female and covers a male end. Work out which one the open connection is before you order.
• Countersunk means the head takes an internal hex key and sits flush or below the port face. Handy where there is no room for a spanner, but you need the right allen key on the truck.
• Still seals on the O-ring at the spotface. Countersunk changes the head, not the seal.

Technicians Advice

Because it sits flush you cannot get a spanner on it later, so make sure the ring is right before it goes in. Backing one of these out of a live block with a worn allen key is not a job you want.

Where You’ll Find It

• SAE O-Ring Boss Male (UNO/UNF) – Cylinder end caps, pump and valve bosses on US-built plant. Common on Australian-assembled cylinders too, where it is usually called UNO.

Cross-Reference

• SAE O-Ring Boss Male (UNO/UNF) – SAE J1926 / ISO 11926 straight thread O-ring boss. Also written ORB, SAE ORB or UNO. Thread form is UN/UNF.

Parker, Gates, Aeroquip and Ryco all manufacture to these same standards under their own part numbering, so a fitting built to the standard above will mate with theirs.

Cross-references are given at series level as a guide to the standard, not as a part-for-part substitution. Always confirm the thread form, size and seal type against the port before ordering.

📐Dimensions & thread sizes – every size in this range

← Swipe the table sideways to see every measurement →

Part code	A	L	AK	Material	Finish
UNM-CS-05	5/16" UNO	10mm	3.18mm	Mild steel	Plated finish
UNM-CS-06	3/8" UNO	10mm	3.18mm	Mild steel	Plated finish
UNM-CS-07	7/16" UNO	12mm	4.78mm	Mild steel	Plated finish
UNM-CS-08	1/2" UNO	12mm	4.78mm	Mild steel	Plated finish
UNM-CS-09	9/16" UNO	13mm	6.35mm	Mild steel	Plated finish
UNM-CS-12	3/4" UNO	15mm	7.92mm	Mild steel	Plated finish
UNM-CS-14	7/8" UNO	17mm	9.53mm	Mild steel	Plated finish
UNM-CS-17	1.1/16" UNO	20mm	14.27mm	Mild steel	Plated finish
UNM-CS-21	1.5/16" UNO	20mm	15.88mm	Mild steel	Plated finish
UNM-CS-26	1.5/8" UNO	20mm	19.05mm	Mild steel	Plated finish
UNM-CS-30	1.5/8" UNO	20mm	19.05mm	Mild steel	Plated finish

Key: L overall length, AK across corners. Measurements in millimetres unless shown otherwise. Thread columns show what each end mates with. Dimensions are nominal – check critical clearances against the part.

Downloads

📄 Thread Identification Chart (PDF)

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