Are plastic knuckles effective because where I live brass/metal

Regarding writing a fistfight, do regular leather gloves protect against bruised knuckles? - Quora

Non-Metal 4-Finger Brass Knuckles Duster Paperweight Self Defense

Round Metal Knuckle Duster Outdoor Four Finger Ring, Self Defense

If brass knuckles are illegal in Canada, why can shops sell them? - Quora

Why are brass knuckles illegal where pistols and semi-auto assault-type rifles are not? - Quora

I made a set of 3D printed brass knuckles based on the set symbol

In What Ways do Brass Knuckles Benefit You?, by Jairus Nadab

Is it an offence to have brass knuckles in Canada? - Quora

If a character were to punch someone using brass knuckles, what would be the effects on their hands? - Quora