This is the APC 12x4 Sport Airplane Propeller.

FEATURES
Lightweight injection molded nylon construction reduces rotating mass
for higher output and longer life
Reinforcing carbon fibers help maintain true, constant pitch at any
RPM.
Gray in color

INCLUDES
APC 12x4 Sport Airplane Propeller

SPECIFICATIONS
Length: 12"
Pitch: 4"
Hub Diameter: 1.00" (25.4mm)
Hub Thickness: 0.46" (11.7mm)
Hole Diameter: ¼" (6.3mm)
Weight: 1.41oz (40g)

REQUIREMENTS
ALL props require balancing, this is VERY important, use TOPQ5700.
May need prop reamer, use GPMQ5006 (SAE) or GPMQ5007 (Metric)