- High-quality door installation kit: the door board lifter is made from high-performance steel, stable and robust enough to withstand impact and bending. Its surface uses a black powder-coated finish with a frosted treatment, offering corrosion resistance and a beautiful textured look that prolongs service life. - Strong and reinforced design: the four corners follow a triangle reinforcement design to resist deformation and improve load capacity. Tested performance shows each installation tool can withstand up to 500 pounds (total 1000 pounds). Edges and corners are processed to be smooth to prevent skin injuries during use. - Fits 1-3/8 inch to 2-1/4 inch doors: compatible with doors from 1-3/8" to 2-1/4" thick. Thickness can be adjusted via a button. A large slip mat area protects the door surface, and the door-contact area uses a non-slip mat to increase grip and efficiency. - Hands-free and easy to use: typically two people are needed, but this kit enables hands-free installation by a single person. No extra accessories are required to get started. The door lifter features four 360° D-rotation wheels with brakes for easy movement and controlled stopping during installation. - Use scenarios: ideal for interior door replacement during home renovation, installing doors in tight spaces, and moving or positioning doors across a room during retrofit projects.