If your thinking of using it for fitness too then your probably best off spending a bit of cash buying some training plates.
£55 will get you a pair of 7lb Beaver Fit training plates from Tactree http://tactree.co.uk/beaverfit-weighted-vest-plates-flat these are flat but will be ok in a quality padded carrier like a 5.11, LBX or warrior and similar.
A word of advice, if you plan to run and train with them in a carrier, run with an empty carrier first to get used to it (you will be surprised at how constricted your chest can feel when your running with one on.)
Then start with one plate and then work up to two. Trust me your knees and back will thank you.
Also consider the quality of your carrier. If it’s a real steel carrier designed for real plates then no problem. If it’s a Chinese made rip off or a cheap airsoft make like Nuprol it’s likely to fall apart and the plate break your toes as it falls out!