I'm after a new locking petrol cap. Anyone have a review or thoughts on these ebay items? Or another product?

1. http://www.ebay.com.au/itm/LOCKING-P...item3a7adba358

2. http://www.ebay.com.au/itm/SL27EC-LO...item3ccb611e05

I'm specifically after how well it seals and also if the curve of the design flows well. ;)