The BMW OEM one (sold in the UK) covers the entire top surface of the bumper from edge to edge, front to back and slightly over the front edge. Mine is now a couple of years old and holding up fine. It is relatively rigid plastic, matt finish, and the front edge of it has a lip that protects that top edge as well.
The actual manufacturer's price on it is a lot more than from a BMW dealership in ENgland. Because of the size (thin, but long), and trying to protect it in shipment, shipping cost could be high. Mine was shipped in a cardboard sleeve and arrived okay via APO mail.
WHy they don't sell this through the USA subsidiary, don't know. Europe has a few other interesting i3 accessories we don't see here, either.
Installation was a snap...it came with a cleaning wipe, use that to remove any wax or dirt, pull the tape off of the double-sided 3M adhesive strips, carefully place it in position and you're done...all of a minute or two. STill holding strong.
2011 535i x-drive GT, 2014 i3 BEV