Grinders or herb grinders are used for crushing and grinding marijuana buds without having to manipulate them with your hands.
It is a cylindrical device with two separable halves. Both halves have sharp teeth or pegs aligned so that when the two halves are turned, cannabis placed inside is effectively shredded.
Some grinders also have two or three compartments instead of one, with a fine screen or mesh that separates the bottom of the upper compartment. This allows small resin glands to pass through and fall to the collecting compartment, while larger pieces of plant material remain in the upper one. They are pollinator grinders .
We can find grinders made of several materials (aluminum, wood, plastic, ...) and even electric grinders for the laziest ones or for those with reduced mobility. Perhaps the most famous brand of grinders is Grassleaf .