For me it was quite clear, at least metal, it should be so that nothing breaks.
A chip should be there as well, so that the camera can use exposure settings and Co..
This adapter ring is the best of its kind of metal and with chip. And he is doing his job wonderfully.
Material is high quality, it fits perfectly and the chip is doing what he should. It rattles nothing, it caught nothing,
the threads are very smooth.
I would pick this ring again when I buy additional lenses of M42 on Eos bayonet. For the price you can
Anyway leave rings on the lens calm. (Nevertheless, it is easy to solve, without going too easily turn off).