Truth 23 Series Rear Mount 11 inch, Single Arm Casement Operator, Left  Hand

Mounting: Rear Mount
Mounting Screw Holes: 3-7/8 & 4-3/4
Arm Length: 11 inch , from center of operator to center of roller
Arm Width: 11/16 inch
Colors: White, Chestnut Bronze or Black
Roller: Stainless Steel
Roller Diameter: 9/16 inch
Handed: Yes, Left and Right - As Shown in Picture

Sold Each, Screws and Crank Handle Not Included

NOTE:
The 11 inch arms are Discontinued by Truth.
The 9-1/2 inch, shorter arm seems to work just fine as a replacement