BuildMOC Compatible Assembles Particles 36840 1x1 Side Bump Plate For Building Blocks Parts DIY Toys Children Gifts|Blocks| - AliExpress
2018 Parts Fest #2: Grantmasters' 1x1 brackets | New Elementary: LEGO® parts, sets and techniques
Is this a legal connection? These are two of piece 36840 (inverted bracket) and System-wise, it shouldn't be a problem, but whenever I try to build it using real pieces (including any