Interchangeability is the key word in describing Xcelite's "99" Series tools. Engineers and technicians prefer these tools because: (1) They can be selected to exactly match the work done, at the lowest cost with minimum size and weight, (2) Tool replacement s quick and economical, as only the blades need be replaced when worn out, (3) Handle and extension versatility (large, small, short, long, "T" or ratchet) is extended to every blade. All blades are high carbon steel. Handles feature a patented spring device that holds blades firmly yet permits quick, easy insertion and removal. Blade lengths range from 4-1/2" - 5-1/2" long.