These blocks are great. I have no issues with the quality of the mirror, the push button block, or the kaleidoscope.
We really enjoy the differences in the blocks and my son particularly loves the bell one and the rattle one. To echo a previous review, it's true that some of them are a bit disappointing but we love Haba brand and this set for the price seemed worth it.
I was so excited to use these blocks as a stocking stuffer for our twins that struggle with SPD and Autism. They seemed like such a fun way to incorporate some sensory stimulation into block building time. The sensory functions for 3 blocks are fine... the bell, the yellow lens and the block with the bead. The other three are pretty disappointing. The mirror block is just a sticker that doesn’t actually reflect anything. The kaleidoscope block is so clouded I would saw that visibility is pretty much zero. The block with the push button doesn’t actually push at all. Our boys will still happily build with them because they love any block. We love TNBC, but this block set was not a great investment for us.