I am using these with the 34mm Diameter Folding Prop Spinner on my Crashtesthobby.com 64" Gladiator. These work really well. I had to set me Turnigy esc to the highest "Brake" setting of Very Hard. My wing weighs 2.3kg and with my Emax GT3520/04 on 3s it has more than 1:1 thrust but i can also turn it down and cruise at 8amps. So very happy with this prop setup.
1) The pair of blades are identical. Meaning if you have another pack of blades for backup, you can use either one of them. There is not a Left and Right blade.
2) The sound is different than an APC prop. I found i liked it a lot.
3) If you are using this in a pusher configuration, as i am, you will need a prop stopper. In a pusher config the blades can over collapse and actually swing over to the other side. Once the majority of the weight is on the wrong side the centrifugal force will keep it on the wrong side and your motor will probably rip itself off the motor mount.
Pic of the spinner, prop, mounting nut, and prop stoppers. And some sticker some guy sent me :)
Prop opening and closing:
Rear view of prop on launch: