The Swanson 24" "Speedlite" Top Read Level is a high-grade aluminum I-beam frame that is strong & lightweight. The vial windows are secured with screws so they won’t pop out on impact like other levels. Rubber shock resistant end caps protect the frame & vials from sudden impacts.,For California Residents:, WARNING: Cancer & Reproductive Harm - www.P65Warnings.ca.gov,WARNING: Drilling, sawing, sanding or machining wood products can expose you to wood dust, a substance known to the State of California to cause cancer. Avoid inhaling wood dust or use a dust mask or other safeguards for personal protection. For more information go to www.P65Warnings.ca.gov/wood Swanson 24" Top Read Aluminum Level