 What are the tangler fields?
The two guards turned to see what was coming in as the three new candidates for the Greensleeves slumped to a stop at the head of the stairs. The outside guard pulled the switch that turned on the tanglefoot electronic fields that swamped the floor of the block corridor and of each individual cell. But it was a rule that, even in Block O, you didn't leave the tangler fields on all the time—only when the cell doors had to be opened or a prisoner's restraining garment removed. It was her first experience of a tanglefoot field. The inside guard finished putting the new prisoners away and turned off the tangler field once more.
 electronic fields near the floor to stop prisoners
 a type of uniform meant to keep the inmates secure  electronic fields in Block O that identify inmates  replacement for guards in Block O  electronic fields near the floor to stop prisoners