Camera dollies’ biggest weakness is their dependance on flat surfaces or large, cumbersome (and not so portable) rails. While iFlow works fine in these conditions, it excels at clamping onto near any flat or circular surfaces you’ll find in the city, be it hand rails, fences, train tracks, two-by-fours, or anything that fits. Soft, shock-dampening (and angle-adjustable) polyurethane wheels, in conjunction with a spring, maintains grip on the surface, though iFlow’s clamps also lock in a more conventional orientation for rolling across flat surfaces.

Hit up Amazon for details – $90