Why does the Erling brick (#4070) have a ridge below its outward facing stud?

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Whereas the more versatile and less common #87087 does not? The #87087 piece also has a better use in SNOT usage, as it can accomadate larger bricks.

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1 Answer 1


The ridge is there to make the base the standard 5LUs wide (see also "What is an Erling Brick"), enabling it to accept the standard stud.

I believe the rest of the brick was thinned out so that the combined "depth" of the Erling brick and a 1x1 plate (its common usage as a headlight) was the same height as a standard brick.

From the HoMa's World of Bricks page on the Headlight Brick:

If headlight bricks are turned over by 90° and a plate is attached to the stud then this construction is as high as a standard LEGO brick or a layer of three standard LEGO plates.

Stacked bricks - HoMa's World of Bricks

It also helps to keep the 1x1 plate straight to the bricks edge.

  • 6
    Good visual explanation. Amazing little brick.
    – LarsTech
    Nov 23, 2011 at 16:57
  • 2
    Props to HoMa's World of Bricks for the image. Nov 23, 2011 at 17:03
  • 1
    I've never seen that brick used that way.
    – Ambo100
    Nov 23, 2011 at 17:51
  • 3
    There are a couple more uses as well. Two Erlings one stud apart can have a horizontal brick connect them. And you can use 8 to make a cube to which 2x2 plates can be attached (about the size of a Lego die). Very useful parts!
    – retracile
    Dec 1, 2011 at 2:22
  • 1
    The first use I personally encountered was in 6394: See the top left corner in step 7 of the instructions: Metro Park & Service Tower
    – Todeswaldi
    Aug 16, 2015 at 9:43

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