[ServoCity]

This coupler is made specifically for the Futaba 25 tooth spline. The 10-32 set screw requires a 3/32” Hex Key . Compatible with our 1/4” Precision Shafts and 1/4” D-shafts.

http://www.servocity.com/html/25t_futaba_set_screw_shaft_cou.html#.U7_snvldV7s