THIS IS A 7-1/2 HP IMPELLER USED ON THE PENTAIR/PUREX C SERIES PUMP. THIS IS THE CMK MEDIUM HEAD IMPELLER. MATERIAL: BRONZE. CLOSED FACE NUMBER OF VANES: 8 OUTSIDE DIAMETER: 5-1/8" (A) THICKNESS: 1-1/16" (INSIDE THICKNESS AT OUTSIDE EDGE) THICKNESS: 1-3/8" (B) (OUTSIDE THICKNESS AT OUTSIDE EDGE) FRONT TO BACK: 2-3/4" (NOT INCLUDING THE EXTENSION ON THE FRONT) THERE IS A 1-5/8" DIAMETER X 3/8" LONG EXTENSION ON THE FRONT OUTSIDE DIAMETER: 4-17/32" INSIDE DIAMETER: 4-5/32" (THIS IS THE PART OF THE IMPELLER WITHOUT VANES)