A cute little device used to castrate a male by means of stretching a small but strong rubber band enough to fit around the base of the scrotum. It is tight enough that it cuts off all the blood to the testicles, causing them to die within a few hours. This process is very excruciating until they're dead, but after which point the body simply adjusts to the new hormone balance. The rubber band can be left on so that the skin dies as well, causing a shrunken, black mass of dead skin and other tissue to fall off within a couple weeks. Should the band be removed before the skin dies, the testes theoretically get absorbed into the blood stream like any other piece of degradable foreign matter. In effect, it then ends up being much like a more painful, drawn-out version of the Burdizzo clamp, with the notable advantage of it being reversible if the subject changes their mind (assuming they're a human with testicles who is getting castrated willingly - not as uncommon as the layperson might think!).