During the past year I've been surprised how many different #0 sized shutters there used to be, I have bought a few #00 as well but there's less choices.
In size #0 I've found and acquired the following, all in good working order:
Compur (there's some variants) - 1 second to 1/300 or 1/500, plus 'B' & 'T'
Copal - 1 second to 1/300 or 1/500, plus 'B' & 'T'
Prontor (Press) 1 second to 1/125, plus 'B' & 'T'
Prontor SVS - 1 second - 1/300 plus B
Pronto - 4 speed 1/25, 1/50, 1/100, 1/200 plus 'B'
Epsilon (and Kodak Epsilon) - 1 second to 1/250, plus 'B' & 'T'
Trikon (Ross) - 3 speed 1/25 - 1/150 plus 'B' & 'T', early versions were known as Ensign Epsilon
Agi - Agifold - 4 speed 1/25, 1/50, 1/100, 1/125 plus 'B' & 'T'
I don't have a Seiko #0. Apart from some early rimset Compur's all these shutters have flash sync.
Perhaps this is a British or European post WWII compatibilty agreement part of standards drawn up just after the war. What it meant was when there were no shutters being exported from Germany Kodak supplied the British made 203mm f7.7 Ektar in a Kodak Epsilon shutter then a Prontor SVS and later the Compur, and then finally the redesigned Synchro Compur
Quite a number of my shutters came from the same source at a camera fair and were from a closed repair shop, some had lenses fitted. They were 3 shutters for £20 ($32), not bad when one had mint 203mm f7.7 Ektar cells and is in perfect working order and accurate .
When I was desparate for a spare #0 shutter I couldn't find one at a reasonable price for love or money, now I keep unearthing them and the last camera fair shutter £3 ($4.80) the Trkon has an un-named coated lens which can only be a 105mm f3.8 Ross Xpres.
The Agifold shutter is interesting as it's two blade and fitted to an aluminium flange using a retaining ring and then to a Bakerlight Speed GraphicAnniversary or earlier lens board, this shutter came off an Agifold 6x6 folding camera originally. AGI still make inspection camera systems but they specialised in aerial cameras until quite recently.
These shutters get used with lens cells bought here or the LFPF.info website, Geronoar, G Claron and others.
The #00 shutters I've bought aren't LF although could be used with some Schneiders like the very early 90mm f8 Super Angulon, 65mm f8 SA etc, I've mint unused Prontors, and good Pronto's, Vario's but sometimes the release mechnaism is geared to a particular camera. I should add that all the shutters and lenses will be used to refrbish defunct/dead cameras.