A sports cart with a folding tubular frame, a central steering column, a pair of real wheels, a centrally located front wheel, a lower basket member, a secondary holding rack, a handlebar assembly, a front wheel fork assembly, a brake member, a steering column to handlebar assembly folding and locking joint and a steering column telescoping member. A steam tube passes through a product line section, transverse to the longitudinal axis, made homogeneously from a single material by cutting with no welded seams. The customer choice model is configured to estimate, for a given customer or group of customers, a likelihood of effecting a substitution between each product pair of the given product and the at least one product similar to the given product, for each of one or more available demand shaping actions. By placing the soluble plug next to an object that is subject to leaking, the soluble plug can dissolve when a leak occurs and release the pressure in the pressure line. Methods of making and using the grafted polymers are also disclosed. In another aspect, the probe contact system includes a conductive elastomer sheet between the contactor and the flexible PCB thereby obviating the top spring of the contactor.