Police web

From Memory Alpha, the free Star Trek reference

A police web was a type of force field used for holding prisoners aboard Kzinti police vessels during the mid-23rd century.

When Sulu, Spock and Uhura were captured by the Kzinti in 2269, they were placed on a police web aboard the Traitor's Claw to prevent their escape. The web was later moved outside of the ship while the Kzinti tested the Slaver weapon they stole from the Starfleet crew they captured. (TAS: "The Slaver Weapon")