This is the 5x3E-B4 Slow Flyer Quadcopter Propeller Bundle from APC.
FEATURES: Long fiber composite construction, gray in color
INCLUDES: Two Standard Rotation 5x3E Propellers
Two Reverse Rotation 5x3EP Propellers
APC LPAR18SF Adapter Rings may be included. If rings
are not included, the propeller has been updated to a 5mm hole and
the rings are not required.
REQUIRES: ALL props require balancing, this is VERY important, use TOPQ5700.
May need prop reamer, use GPMQ5005 (SAE) or GPMQ5007 (Metric)
SPECS: Hub Diameter: 0.50" (12.7mm)
Hub Thickness: 0.23" (5.8mm)
Shaft Diameter: 1/4" (6.3mm)
Weight: 0.11oz (3.1g)
COMMENTS: For use with electric motors only. Do not use with gasoline or glow