The reflector screen kind of does both. Kindof complicated to describe it more accurately. Basically it doubles gain in one direction while reducing gain from the backside.
The blocks are PVC which isolates the elements and transmission wires from the metal mast (which leads to ground) as this would short the electrical transmission of the signal, and seriously reduce the performance. It is also hydrophobic which is also advantageous on the electrical transmission side, when it gets wet from the rain.
It's pretty sweet, all Zinc Galvanized (screws and washers are plated) Steel with PVC blocks. Mounts to a mast with standard hardware...wall mounts, eaves mounts, the works. Screen is easily removed if you want a more bi-directional pattern.
It even has quick wingnut mounts for the matching transformer.
Panasonic AX-200u / Optoma Graywolf 92" / Draper Luma 92"
Samsung 51F8500 Plasma / Vizio M422i LCD / Vizio GV42LF LCD / Vizio VP322 Plasma
Sony S790 BD / Panasonic BDT220 BD / Roku 2 XS & HD-XR / PlayStation 3
Oppo 983H Anchor Bay VRS / Denon 2930CI Silicon Optix Reon / Panasonic S97 Faroudja Genesis / Oppo 970HD Mediatek
Panasonic LX-900 Laserdisc / Aiwa MX100 Multi-region VCR / JVC S7600 S-VHS