TZK-2M ventilation suits appears to be a further development of the VK-3M ventilation suit, designed to be used with the VMSK outfit. It's made out of much warmer material and externally is very similar to its predecessor with the exception of the TZCh-2 socks. While they come separate from the suit and attach to it via laces, suit was really meant to be worn with these socks attached as ventilation system extends all the way into the them and otherwise would be needlessly hanging from the top portion of the suit.

A lot of people think TZK-2M is an optional suit that could have been either worn or left out from the VMSK at pilot's discretion. I believe this is not true. VMSK outfit is extremely warm and I doubt any pilot would feel comfortable wearing it after a short period of time. TZKM-2M's ventilation system keeps temperature inside of the VMSK-4 outfit at a reasonable level during the flight and, in case pilot ejects, its warm material becomes yet another barrier from the cold water.

 

Overview of the TZK-2M suit with TZCh-2 socks. On the left side suit is as viewed from the back, on the right - from the front.
Located on the inside back part of the suit is its ID tag. First line is the name of the suit, second is its serial number and third line is the size.
Close up on the right chest area. Note two small openings - one on the upper portion of hand, second is on the right side of the chest. Located right under the chest opening is a small pocket.
Left chest side of the suit has similar opening as the right one, but notice that it doesn't have a pocket.
Just like on VK-3M, left waist size of the suit has an opening for the VKK-6MP-1's or PPK-1UK's tubes.
Both of the suit's sleeves end up with a small strap that should be put around pilot's palm when he dresses up in TZK-2M.
Shown here is yet another visable difference between VK-3M and TZK-2M suits. While VK-3M has a regular suit connector, TZK-2M has only a small tube coming out from its ventilation system. Unlike VKK-6MP-1's tubes, which go all the way through the orange VK-4 suit, TZK-2M tube connects to a special seal inside of the VK-4 suit.
TZK-2M's ventilation system can be accessed both from the inside (just like on the VK-3M), as well as from the outside. Shown on this picture is an outisde material cover placed over suit's tubes - to access them, one only needs to untie several laces.
Close up picture of the right TZK-2M sock, known under the TZCh-2 designation.
ID stamp located one the right sock. First line is the name, second line tells if it's right or left sock and third line is it's size.
Socks can be untied from the suit and replaced with new ones.