This is replacement cap for your disposable water bottle. From the website:
Why not use it to defend yourself? The Bottle Bezel has a checkered, “tenderizer” top surface, with 6 serrated, trapezoid petals that surround it. It can be used 4 standard ways, regular grip, inverted grip, gouging mode, or as a weighted flail with accessory lanyard.
I believe that you can probably get some self-defense value out of a water bottle, but just making the cap bumpy or pointy isn’t going to be enough. I hadn’t really considered using my water bottle as an improvised weapon since it is usually only in hand when I am drinking out of it.
Weaponized bottle? My standard water bottle is stainless steel. I bought mine to carry liquids in volume so it is a bit bigger (40oz.) than most regular water bottles (32oz.) but it would hit like a bat and be in no danger of breaking. I suppose I could down size it to the 27oz. size and it would be a little more suited to gripping.
Weaponized cap? The standard cap doesn’t have anything to scratch the opponent or whatever the “Bottle Bezel” is supposed to do for you but I am sure getting hit with the business end of the cap full force would probably leave a mark. I think I am going to stick with actual weapons rather than trying to make every day items into weapons.