Diamond produces the largest selection of preassembled doors in the industry. Preassembled doors differ from knock down doors because they are completely factory assembled including all hardware, lite kits, and a subframe system (c-channel/framed opening). The installation time for preassembled doors averages 35 minutes so compared to knock down doors, this might mean 4 to 8 hours of immediate labor savings. Preassembled doors are also beneficial because all hardware is guaranteed to be installed correctly and in good working order. Comparing the total preassembled and knock down costs over time, including the cost of call backs and lost parts, a preassembled door may be some builders best option.