Abstract: A cutting apparatus of a type having two juxtaposed blades 1 and 2 with each having an outermost cutting edge with teeth 12 and 13, with retention and driving of the blades adapted to effect an oscillatory motion to each of the cutting edges, characterized in that there are means to resist resonant spreading between the blades 1 and 2 when cutting which are that there is a first of the blades 1 having a first portion supported by the first blade with a part 15 which is positioned behind a part 18 of the other blade, and a second blade 2 includes a portion with the part 18 which is positioned behind the part of the first said blade.

Abstract: An air board including a platform upon which an operator of the vehicle can be supported; and a support arrangement for providing an air flow for supporting the platform above a surface, wherein the direction of movement of the air board is at least partially controlled by varying the weight distribution of the operator on the platform.