I'm probably overthinking this but....Part 2108T21 is .79 inches which works out to 20.66 mm, which as Volt stated is perfect for the CM3's which are 20 mm. I'm thinking about pulling the trigger for part number 2108T24 for the KM184's - .87 inch which works out to 22.098 mm. The 184's are 22 mm, I'm just concerned that the additional .098 mm won't be big enough to accommodate the Neumann logo badge that is affixed to the body. Oh well, the tubes are certainly cheap enough to give it a shot.
The length of a CM3 + 184 is a total of approx. 7 1/4". The cigar caddy is 8" long (I assume OD). So I'm keeping my fingers crossed that the 2-cigar caddy will hold both the CM3's and the 184's. If I can fit both sets securely in the 2-cigar caddy, I'll be golden.
Will report back how it goes
On voltronic's recommendation I picked up a couple of the 2108T24 also for my KM184s that will go into my pelican micocase. They should be here today, I'll report on the fit with the Neumann logo badge too!
Also, please note that the website won't calculate shipping. I placed my order today then asked them via the "Contact us" on the site. Got this response:
Hi Daniel,
The estimated shipping cost for your order is $7 and the order will deliver on Monday.
We calculate the shipping charges based upon the actual size, weight and number of packaged required to ship your order.
Until we finalize the ability to obtain shipping estimates on our website, please feel free to e-mail us for a shipping estimate.
Brian
Ordered four of the tubes; order under $6. I guess having anything shipped for $7 these days isn't terrible. They sure were fast getting back to me.