This movie (set in the future) starts out in a remotely located prison where each prisoner wears a collar. Each collor is secretly linked to another. If the linked collars get 300 feet apart, or away from the prison preimeter, they explode. I THINK the prison officials rig it to let a certain con escape, hoping he will lead them to SOMETHING ( I forget most of the details). This movie was possibly from the eighties. Hoping someone can name it. Thanks in advance to anyone who can help.