Barnett has changed the design of its models several times over the last years. Its (achieved) goal to produce very ergonomic slingshots brought three generations of each model. The latest have rubber pieces included in the handles, and Cobra and Diablo share a similar body.
These are the three generations of Strikenine, the one to the right in production. The Black Widow models are the same, just with attached wristbrace.
There are two kinds of old Diablos. The first one has a metal frame with plastic parts at the side of the handle. The second version offers a wood-like ventilated handle (I don't know if it is wood or some wood-epoxy-compound).
