3/16" heavy duty backing plate adds strength & stability and prevents Set includes: 3/4", 7/8", 1", 1-1/8", 1-3/8", 1-1/2", 1-3/4", 2", 2-1/8", 2-1/2", 3" hole saws + 3/8" Quick Change Mandrel & 1/4" Hex Shank MandrelItem: 13PC M3 Bi-Metal Hole Saw Kit 628204614900