A grinder is a device to finely grind herbs, ( shred in little pieces )predominantly for grinding herbs like marijuana ( cannabis ) or tobacco.
The most simple herb grinders usually consists of two round disks, sometimes they can be magnetized, each of these round disks have small pins underneat them, blades, or "teeth" . The chosen herbs are placed in the cavity between the two halves and the grinder is repeatedly twisted until satisfaction. Moving in opposite directions, the herb is cut up by the grinder's rotation. This results quickly fine herb shreds, which can be used to put in a bong, or roll in a paper.
Some grinders have a screen beneath the grinding pieces, used when grinding marijuana to catch the trichomes that fall off and trap them in the encase compartiment. This is a very good way to produce some "crystal", after a few usage of the grinder there will be enough crystal in the compartment and you can use those thc crystal in combinaison with the normal herbs, THC concentration will be much more potent.
Grinders comme in many different shapes and materials, you can easely find grinders made in wood, plastic and metals. Metal grinders are more durable, but lower end quality metal grinder tend to lose its metalic coating, which can stick to your hands or the herbs. Wood grinders are more fragile but , they will wear off with time. As for plastic grinders, these allow you to use transparent plastic so you can see the herb in the grinder, although it will need frequent cleaning.
