Thunderbolt 3 (40 Gbps) Extension Cable (male/female)?

Thanks, but I need "TRUE Thunderbolt 3 (40 Gbps) supporting also USB 3.1 Generation 2 (10 Gbps) as iMac (2017) supports", as said above. That means a true full Thunderbolt 3 cable or adapter. All such devices need Intel certification (Intel charges 33,000 dollars to manufacturers just for such certification!) and they have the Thunderbolt 3 logo.

The one that you indicate at Amazon as "UGREEN USB C Extension Cable Type C Extender Cord Male to Female Compatible with Thunderbolt 3" is not Thunderbolt 3. It is USB 3 generation 1 with USB-C port, and it supports only 5 Gbps. It says "Compatible with Thunderbolt 3", meaning that you can plug it into the Thunderbolt 3 port, but it is not Thunderbolt 3. The fact that both Thunderbolt 3 and USB 3.1 Generation 2 use USB-C port is generating a lot of confusion, and this is an example of it.

Thanks, but that is not what I want. As said above, I want Thunderbolt 3 (40 Gbps) Extension Cable (male/female). That means:

Thunderbolt 3 MALE ============<this is a cable or adapter>============ Thunderbolt 3 FEMALE

Where to purchase it?

Who makes them? I just need a short one. Half a meter or less will be fine. It must be TRUE Thunderbolt 3 (40 Gbps) supporting also USB 3.1 Generation 2 (10 Gbps) as iMac (2017) supports:

Either a cable or adapter (1 male --> 1 femakle)

Thunderbolt 3 MALE ============<this is a cable or adapter>============ Thunderbolt 3 FEMALE

or a duplicator (1 male --> 2 female)

/============<this is a cable or duplicator>============ Thunderbolt 3 FEMALE

Thunderbolt 3 MALE /

\============<this is a cable or duplicator>============ Thunderbolt 3 FEMALE

Thanks. Do they make adapters for that? I do not mean full hubs or docks, but just adapters for that (if they do not make cables, as you say).

Or Thunderbolt 3 port splitter duplicator?

Also useful would be:

Thunderbolt 3 FEMALE ============<this is a cable or adapter>============ Thunderbolt 3 FEMALE