im guessing its an english metric size..!

most likely a john gray or older premier etc..

i had a cpl toms...that were 12/13...but when i reskinned them..nope...!

the skins were to big..

is the kit older...50s/60s..?:p

I don't know. It belongs to a student of mine and she has no idea where it came from. No name on it either. I have not seen it, but it is, more than likely, a cheap kit. The snare was a 6-lug with very cheap hardware that had no markings.

Remo can make them on special order but I've heard it takes months (has to fit into their production schedule). Also, you need to be sure it is exactly 21" and not a pre international size which is close but not exactly it.

http://support.remo.com/remoinc/topics/pre_international_heads_for_premier_kit

And if it really is 21"?

Believe it or not, DW make a 21" bass drum so they must have some. At a price...

http://www.dwdrums.com/drums/collectors/specialty.asp

And at an even more outrageous price:

http://www.ebay.ca/itm/RARE-Vintage-Gretsch-Bass-drum-HEAD-w-SCRENNPRINTED-LOGO-21-Rare-60s-leftover?item=261148509887

(originally found by Kona in this thread and this last one is a bad joke not real -- you have to read the thread)

I could be wrong, but I think that the DW Gong drum is a 21" shell, with a 22" bass drum head, or possibly a tympani head stretched over it. As to standard bass drums, they list many diameters on their website (including 23", oddly), but no 21" bass drums are listed.

Regarding that overpriced 21" Gretsch head, I'll believe it when I see a tape measure across it. My guess is it's a 20", and it was measured from the outside of the flesh hoop.

I picked up an identical head on Seattle Craigslist for FREE a couple months ago.

Firstly, make sure it is actually 21". There were drums made in Germany , in the 50's that were 540mm or 21 1/4". These were made by Tromsa and possibly others and often didn't have badges. Tromsa used the logo on the heads as their badge sometimes. These are better drums than one might think at first glance.

If the drum is actually 21"---you may be in luck. Remo makes a 21" Tympani head. Some Tympani heads have an insert, which is used for pedal tuning but there are also some without inserts. Tympani heads are the same mil thickness as a Diplomat----7.5mm , so the TI 2100 comes in clear and hazy and is essentially a 21" Diplomat head-----not perfect ,imo for a bass drum but at least it is a head.