Allows the contractor to comply with 2005 NEC Article 314 20 Works in handy boxes and 4 Inch square electrical boxes with plaster rings for single switches or receptacle Manufactured from 105 degree C continuous use 94VO rated flame retardant plastic for safer installations Functions with all standard devices Switches and GFCIs Levels and supports the wiring device where the box is set back from the wall surface (adjusts up to a 1-1/2 Inch box extension).