When securing components inside a mechanical housing, you need a fastening solution that is reliable, space-saving, and capable of handling high rotational forces. Enter the internal circlip—also frequently called an internal retaining ring.

Though small and often hidden from view, these components are vital to the structural integrity of automotive transmissions, electric motors, and heavy machinery.

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What is an Internal Circlip?

An internal circlip is a semi-flexible, engineered metal ring with an open end. Unlike external circlips, which stretch open to fit over a shaft, internal circlips are designed to be compressed inward. They are installed directly inside a cylinder, bore, or pipe housing.

Once fitted into a specially machined groove inside the bore, the ring snaps outward. This creates a strong, rigid shoulder that prevents bearings, pins, or gears from slipping out horizontally.

       [Housing Wall] 
  _______________________

 |   __  [Groove]  __   |
 |  |  |          |  |  |
 |  |  |==[CLIP]==|  |  | <--- Fits tightly into internal groove
 |  |__|          |__|  |
 |_______________________|

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Key Mechanics and Design Features

• The Lug Holes: Look closely at an internal circlip, and you will notice two small tabs with holes at the open ends. These are lug holes. They allow specialized pliers to grip the ring securely during installation and removal.
• Sizing Rules: Internal circlips are always categorized and purchased by the nominal bore diameter (the inside diameter of the housing), not the diameter of the groove or the uncompressed ring itself.
• Tapered Design: The ring’s width decreases from the top center down to the tips. This specific geometry ensures that the circlip maintains a perfectly circular shape when compressed, distributing pressure evenly across the housing groove.

Our Internal Circlips are available to purchase directly online.

D1400 are External Circlips and D1300 are Internal Circlips, and are the most popular form of Standard Circlips.

The D1400 External Circlips are the same as DIN 471 External Circlips and are designed to be fitted on to shafts with grooves.

D1300 Internal Circlips are the same as DIN 472 Internal Circlips are are used within bores with grooves.

We stock these Circlips online in Carbon Spring Steel and Stainless Steel. However other bespoke materials can be quoted for, including Inconel, Titanium and Phosphor Bronze.

To order directly online, please follow this link below.

We stock one of the UK’s largest range of DIN 471 External Circlips in both Carbon Spring Steel and Stainless Steel.

DIN 471 is the standard for External Circlips and makes up the D1400 series of Circlips.

We’ve made it simple to browse and shop our full range of DIN 471 External Circlips online. Simply follow the links below.

Internal Circlips are an open ring with two lugs at the end, facing internally.

These circlips are designed to be fitted into bores with the circlip fitting into the groove of the bore.

The internal lugs allow the circlip to be compressed with circlip pliers to aid with the installation and removal of the circlip.

Materials available for internal circlips include, carbon spring steel, stainless steel (including 316 grade stainless), inconel and titanium.

Other varieties of internal circlips are also available, including inverted lug and increased abutment circlips.

View our full range of internal circlips online using the link below.

Have an enquiry for internal circlips? Please contact us today, and we will be happy to help.

We stock one of the UK’s largest range of External Circlips – designed for shafts with grooves.

Our range includes:

• Metric DIN 471 (D1400) in Carbon and Stainless Steel
• Imperial N1400 in Carbon and Stainless Steel
• Inverted (Balanced Lug) M1408 & N1408
• Increased Abutment (D2100)
• Grip Rings
• Crescent Rings

Shop our wide range directly online, and receive the next working day.