The portable toilet is used on construction sites and at large outdoor gatherings where there are no other facilities. They are typically self contained units that are made to be easily moved to different locations as needed. Most portable toilets are unisex single units with privacy ensured by a simple lock on the door. The units are usually light weight and easily transported by a flatbed truck and loaded and unloaded by a small forklift. Many portable toilets are small molded plastic or fiberglass portable rooms with a lockable door and a receptacle to catch waste in a chemically treated container. If used for an extended period of time they have to be cleaned out and new chemicals put in the waste receptacle. For servicing multiple portable toilets tanker trucks, often called "Honey Trucks", are equiped with lage vacuums to evacuate the waste and replace the chemicals.