Comparison : Item # SDB500, Spade Drills, thickness 0.1035 / 0.1135 in
Item # SDB688, Spade Drills, thickness 0.135 / 0.145 in
Item # SDB938, Spade Drills, thickness 0.165 / 0.175 in
Item # SDB1.375, Spade Drills, thickness 0.197 / 0.207 in
Item # SDB1.875, Spade Drills, thickness 0.260 / 0.270 in