The following information I copied from the Rosen Stamp site. It helps with basic identification. I have highlighted in red the pertinent quality that I can see in your pic. That being your stamp has the "inner vertical frame lines". Note, they are listed below as "inner frame lines".
As you can read below, having inner lines means the stamp is #10A or #11A. With sinclair2010 telling us it doesn't look like an Orange Brown, that eliminates the #10A.
Quote:
10 3 cent Orange Brown type I, plates 1E & 1i (E for early, I for intermediate states of the plate). No inner frame lines.
10A 3 cent Orange Brown type II, Plates 1E, 1i, 2E, 5E, 0. Stamps with inner frame lines. Note that some plates have stamps of both types.
11 3 cent dull red (1855) type I, Plates 4, 6, 7, 8. No inner frame lines.
11A 3 cent dull red, (1853-54-55), type II, Plates 1L, 2L, 3, 5L (L for the late state of the plate). Stamps with inner frame lines.