Covers 6X9 cm. Excellent little shutters for 150 G-Claron and others that require a Copal 0. Lens is a cheap little Tessar type that was in a military industrial application camera doing polaroids of finger prints or some such.
I have one, purchased off of Ebay, a year or two ago. It's a wee little thing, but it will cover 4x5 up close. The limited shutter speeds won't be a problem, if you're using it in the studio with strobe, or for long exposures. And again, it's a Copal ) size shutter, and as such, you could mount another lens into it, if you needed to.