Flat mantlet
The left side of the mantlet is flat except for the outer ridge. It may be completely smooth, or may have subtle raised areas, depending on how it was cast.
Thickened mantlet
On the left side of the mantlet, there is a thick ridge containing the two telescope eyeholes. The exact shape of the ridge depends on how it was cast.
Tiger (P) mantlet
The mantlet was designed for the Tiger (P). It has no thick ridge on the left side. There is a notch at the bottom left corner.
Raised panel mantlet
On this mantlet, there was a raised panel on the left side, outboard of the eye holes. It probably existed due to the vagaries of the casting process.