Plastic kubotans or kubatons are just another form of the keychain that are usually made of polymer. Although they are not metal they are still very hard and solid. They have the same dimensions of the standard metal kubaton.
The polymer kubotans are usually much lighter than the metal ones, which makes them an easy everyday carry but could hinder their ability to deliver some techniques, like fist loading to give an example. They are still excellent for jabbing, stabbing and other types of techniques like locking and anchoring. They are good tools to use for self defense, however not the best choice if the sole purpose is self defense when compared to the metal ones.
They also come handy while traveling or while visiting places where you want to avoid the noise made by metal detectors.
If you decided to pick a plastic kubotan, then one thing to consider is that your kubotan needs to be grooved to minimize the possibility of slipping if your hands got sweaty. Quality is very important factor here to compensate the loss of weight.
In short, they are lightweight and solid tools, that are still good for self defense.
…. STAY SAFE …,,