Key innovations of the GH2720QR Bird Watching head, are the new Bird Watching Fluid Cartridges, the Single Lock System & the ultra-precise inner mechanism. Pan & Tilt Fluid cartridges are completely new & offer a completely opposite behaviour than the traditional video ones. These innovative cartridges guarantee a ultra smooth & controlled movement at very low speed (exactly what Bird Watchers are looking for), while at high speed the movements become almost completely free, & this is