We've been using Shinwa's 3D squares and gauges for years, and this is a new release from them.
This gauge is designed to be used with 4x2s, and all measurements are derived form it's 89mm width.
The perimeter of the tool gives an accurate 45 and 90 degree measurement, as well as a 150mm ruler.
Rectangular holes appear in both faces of the gauge. These are for marking lap- and finger-joints depending on whether you would like to subdivide your joint into 2, 3 or 4 parts.
The circular holes in the gauge are used to mark screw spacing.
Overall Dimensions are 178×92×51mm.