Charcoal disks allow you to burn any dried herb, resin or incense powder with ease. Simply place the disk in a heatproof dish or bowl, light with a lighter until the disk sparks (20 seconds or so) and then put a pinch of herbs, resin or powder on top.
These disks stay lit for about 30 minutes. Then, they turn to ash and can be disposed of easily. Be careful when using charcoal disks as they get very hot. Do not touch the vessel holding the disk once the disk is lit. Use only in a heatproof container. They are not safe for use with glass.