The Ranvoo bumper and the Thanotech K11 are only similar because both have metal parts. However the K11 TPU margins are much larger than those on the Ranvoo and there are more of them. The oval shape holes at the lower corners of the Ranvoo do little to help with the signal. The k11 is stainless steel not aluminum like the Ranvoo. If there is signal degradation with the k11 it is certainly less than the Ranvoo. The k11 isn't out yet because, as they informed me in this direct quote, it's a problem with manufacturing.
"Thank you for reaching out to us! We would or course love to have that new bumper delivered to you as soon as possible. There have however been a couple of delays with the Manufacturers that are out of our control so unfortunately a delivery near the first of the month does not seem likely."