Manual grinders are simple tools used to grind coffee beans, spices, or grains by hand. They typically consist of a hopper to hold the material, a grinding mechanism, and a handle for turning. Users can adjust the grind size by changing the distance between the grinding surfaces, allowing for a customized texture. These grinders are often favored for their portability and ease of use. Unlike electric grinders, manual grinders do not require electricity, making them ideal for camping or travel. They also tend to be quieter and can provide a more hands-on experience for enthusiasts of coffee or cooking.