Rebar positioners come in various forms, including spacers, chairs, and ties. Each type serves a specific purpose, depending on the project requirements. Spacers, for example, maintain the correct depth of rebar in the pour, ensuring that the bars are adequately protected from environmental elements. Chairs are used to elevate the rebar and keep it off the ground, preventing contamination from soil or debris. Ties, on the other hand, help secure the rebar in place, ensuring that it does not shift during the concrete pouring process.