8926 and the 8926OB are both 40mm.
One has a scalloped Bezel.
OB has a Coin Edge Bezel.
A typo in another post, had me digging for 2-hrs on this model.
That the watch came in 5 options.
8926 A: all STST with a Black Face & Scalloped Bezel.
8926 C/OB: all STST with a Black Face & Coin Edge Bezel.
8927 A: STST and Gold with a Black Face and a Scalloped Bezel.
8928 A: all STST with a Blue Face & Scalloped Bezel.
8928 C/OB: all STST with a Blue Face & Coin Edge Bezel.
You can search the 2011 catalog, in the sticky's at the top of this forum.
Lo-pdf is the same as Hi-pdf, just loads quicker.
Or, SEARCH, at Invicta's site,8926, it will show both as a result.
In both the catalog, and IWG Site, the 8926 & 8926OB are listed as 40mm.
Adding, when you measure the coin edge bezel with a vernier caliper, it's a continuous circle of points, you will always get 40mm.
A scallop bezel, will measure 40mm at the points, and 38mm, on the flats.