I'm hoping that you meant "the plural of MK 4"
Probably so, since most folks don't even realize those other cardioid variants even exist!
Here's something I wrote to a TS member about different Schoeps active/remote setups:
Basically, there are two main Schoeps mic systems:
1. CCM - compact condensor microphones, these are complete mics by themselves and so there are no 'caps' that can be switched. They come as hardwired (Ug) or with lemo-cables (Lg) that come either unterminated or with XLR (x2) ends from Schoeps. One thing I've done recently is have the XLR ends removed and reterminated into a TA5 (5 pin mini-XLR connector) so that I can use it with a Tinybox. CCMs require 12V or 48V phantom power.
2. MK modular capsule system. This is the system that has the MK4 and other interchangeable capsules that can screw onto either a mic body (CMC4/5/6) or a connector. The MK+CMC is the classic type of mic+capsule, like the CA-11 with cardioid/omni caps. Alternatively, instead of screwing the cap directly onto the mic body (which can be more bulky obviously), you can use a variety of alternative connectors that look very similar.
They are:
a. KC5 active cable - this is the cable that has a connector for the MK capsule to screw onto, a connector to screw onto the CMC mic body, and 5 meters of cable in between the two. This allows you to keep the caps separate from the body for greater versatility and convenience. The mic bodies are connected via XLR cables to a pre/recorder that provides phantom power (P12/P48). This is how I ran my MKs when I had the MK/CMC setup.
b. KCY active cable - this cable is similar to the KC5 cable. It has two connectors to screw the MK caps onto, 5 meters of cable, and then a KCY connector at the end. The KCY connector connects to one of several devices, including the Schoeps preamps (VMS02ib, VMS5U, etc.) and some other non-Schoeps preamps, like the 'Lemosax' (a variety of a Sonosax preamp). These Schoeps and non-Schoeps preamps take the place of the mic bodies, so you don't need the CMC bodies with this KCY setup.
c. CMR non-active cable - this cable has a connector that screws onto a MK capsule on one end and 5 meters of unterminated cable on the other, which has been terminated to a TA5 by Darktrain and others so that it can be run off of 9V plug-in power from a Tinybox (not phantom power). Here also, no mic bodies are needed, you only need the CMR cables and the Tinybox. The downside is that the CMR/MK have a lower sensitivity (40% I think I read) so that may make it noisier if you are recording quieter music. This has become pretty popular this year.
d. Nbox - I'm not sure what cable is used for the Nbox, but it has Schoeps connectors at the end to screw onto the MK caps, and the cable plugs into the Nbox which powers it and provides gain. It's a bit bulkier though IMO.
The most stealthy of these options is the CCM>Tinybox and the MK/CMR>Tinybox setups, because the Tinybox really is very small (2/3 the size of a PCM-M10) but the Nbox has been used a lot by stealthers also. The preamps (Lemosax, VMS5U, etc.) are rather bulky and not really suited for stealthing.