5/16" ZN Quick Link
4-Inch Stainless Steel Shank with 1/4-Inch Bore
DEWALT DW1803 Heavy Duty 7/16-Inch Shank Quick Change Mandrel (Fits Hole Saws 1-1/4-Inch - 6-Inch)
The Hillman Group 45201 3/4-Inch Stainless Steel External Retaining Ring, 7-Pack