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What is the 4-Hole AMPS Pattern?

What is the 4-Hole AMPS Pattern?

Posted by George on 14th Jan 2019

Many of the components and mounts in our range refer to a 4-Hole AMPS pattern. There is no defined standard for GPS mounts in the same way that the VESA exists for monitor mounts. Device manufacturers such as Garmin and TomTom have settled on the 4-Hole pattern in their device cradles and it has become a default standard in the market over time.

The AMPS hole pattern consists of four holes arranged in a rectangular pattern that are spaced 38mm x 30mm (1.188" x 1.5") apart. Some cradles and components only have a 2-Hole AMPS pattern which describes the diagonal of the 4-Hole version with 2 holes spaced at 48.5mm (1.912") apart.

AMPS Hole Pattern

There are many bases in the RAM Mounts range that are manufactured to comply with the AMPS pattern, making them ideal for mounting devices that include the pattern in their cradles and casings.

All of our BikePenR custom GPS mounts and many of our RAM Mounts and Ultimateaddons components are compatible with the AMPS hole pattern. Some of the products that include the AMPS hole pattern include –

  • Garmin zumo motorcycle GPS cradles
  • Garmin Montana Rugged Mount & Cable
  • Garmin Montana Handlebar Mount
  • Garmin InReach AMPS Powered Mount
  • TomTom Rider motorcycle GPS cradles
  • All RAM Mounts Device Specific Cradles


  • RAM Mounts offers 3 different options for attaching mount components to device cradles with the AMPS hole pattern.

    The RAM-B-347U is a rectangular base plate with the 4 holes arranged in the standard 38mm x 30mm pattern. This is commonly supplied with Garmin zumo motorcycle GPS devices and is the preferred mount option for all the Garmin accessory cradles.


    RAM-B-347U Hole Pattern


    The RAM-B-202U Round Plate has 7 holes allowing the base to be rotated to suit the rectangular or diagonal configuration of the AMPS hole pattern. This is commonly supplied with the TomTom Rider 400/450/550 motorcycle GPS devices. The round plate is also used for most of the RAM Mounts tablet holders. This plate also works well for surface mounting to hard surfaces.


    RAM-B-202U Hole Pattern


    The RAM-B-238U Diamond Plate has 2 holes arranged in the diagonal of the 4-Hole AMPS pattern with 48.5mm spacing between the holes. This mount is commonly attached to the smaller GPS and Phone device specific cradles and a selection of universal holders from RAM Mounts.


    RAM-B-238U Hole Pattern


    The UA-25AMPS 25mm to AMPS adapter is a clever way to build a compact mount kit for devices that have a 4-Hole AMPS pattern. The adapter is made from high strength composite with the 4 holes arranged in the standard configuration. Simply bolt the adapter to your device and then insert a RAM Mounts or Ultimateaddons 25mm ball mount into the socket and you have a compact mount solution ideal for motorcycles.


    Ultimateaddons 25mm to AMPS Adapter


    Simply measure the hole spacing on your device or cradle to determine if the holes are arranged in the AMPS pattern. You can then select from the many options in our store to build a complete solution.

    As always, please contact us via email or call our friendly staff on 1300 557 285 if you need assistance in building a custom device mounting solution for your motorcycle.