A concrete form having a tubular body formed from a flexile strip wound helically in successive passes to define a wall of the form. The cathode catalyst includes a support having at least one transition metal in elemental form and a chalcogen disposed on the support. A current transformer is coupled to the output of the transfer switch and generates a load measurement signal that is proportional to the current or power output from the transfer switch. A cathode electrode is connected to the underside of the n-type InP substrate. Once the engagement cam system rotates the at least one bearing into place to receive the at least one steering cam, rotation of the steering cam independently alters the speed of one drive wheel in relation to the other drive wheel in response to steering input provided by the operator.