I bought the cheapest ones a few years ago, and they seemed alright. Was just wondering if these cheap ones with electrical contacts actually work:)
read reviews on amazon.
they work.. and sometimes they don´t if you stack them.
a friend has cheap ones that bend so much when he stacks all three, one pin will loose contact.
or better say the pins are to short to begin with.
it´s just contacts.. no electronics.
but some cheap chinese companys can even mess up that.
i can only speak from my own experience and my kenko tubes sit tight and work flawless.
i have no complains.