I bought a crate of Lego's from a flea market, and it has this strange block inside it. It's a transparent blue color, round, and somewhat thick. It seems to be a single piece, I can't find anywhere to separate it. It has wiring inside of an unknown purpose, and I can't see anywhere to connect to the wiring, so I am assuming it's some kind of wireless thing, but I can't imagine to what end. There are at least 3 of them that I have found so far, and they all have different numbers on them - 40R5, 30R5, 16R5, and some smaller numbers that I couldn't quite make out. There is a shallow circle hole on the bottom, but it's just barely too small for a normal brick "dot" to fit into.

I'm curious what these are for, and what set they might have come with.

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  • that's an RFID tag
    – jsotola
    Commented Sep 7, 2023 at 18:01

1 Answer 1


After posting, I was finally able to manipulate the image enough to get the right part number (or part of a part number) and found out that it is 18602c01. It's a generic gadget base. This base is part of a LEGO Dimensions video game which had different characters, and you could put the unique base into a Lego Dimensions Toy Pad that would detect which character it was (hence the wireless stuff inside). You could then play as that character in the video game.

I'm assuming the other larger lettering (30R5, etc) are designations indicating the character the base belongs to.

As pointed out by Alex in the comments, the 30R5 etc. codes are manufacture dates.

  • 1
    30R5 - is a production week. In this case it is 30th week of 2015.
    – Alex
    Commented Aug 28, 2023 at 15:29
  • 1
    IIRC the wiring is a standard NFC tag, though it's been years since I've played with them so I might be remembering incorrectly. Commented Aug 28, 2023 at 15:38
  • That makes a lot of sense, @Alex, thanks. I wonder how you are supposed to know which base goes to which gadget, once they are apart? Commented Aug 28, 2023 at 16:27
  • I remember scanning couple of these generic tags I got from Bricklink with smart phone only to find they are all the same. I haven't played the game, but it makes me thing generic tags/bases are somehow tied with character tag/base.
    – Alex
    Commented Aug 28, 2023 at 20:40
  • 4
    @AustinHemmelgarn they use NFC. I just checked one tag/base with my phone. And it also says the tag is "writable" so, I guess, it can be reused for something else. I don't have any of character specific ones to check though.
    – Alex
    Commented Aug 29, 2023 at 5:45

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