You can buy different types of props for the H109s, the stock props are plastic and are flexible resulting in the loss of lift and the drone being slightly unstable in windy conditions. The best type of prop that I have used are carbon fibre props such as these ones;

DJI Phantom 3 Carbon Props on Amazon

The above props are well balanced and perform excellently on the H109s. However these are very expensive. You can get cheaper carbon fibre props such as;

After-market Carbon Fibre Props

These perform just as well but may not be balanced. You could even go for a 3 bladed prop such as;

3 Blade Carbon Fibre Props

I’m not sure how these perform, if you have experience of using them maybe you could let me know.

Carbon fibre props are very rigid so don’t get your finger caught in them and very brittle if they hit the ground they will shatter and be unusable so be careful with them.

If you need something cheap you could get;

Cheap Plastic Props (not recommended)

Be careful with these as they are very flexible and your drone will be unstable in windy conditions or if you fly it hard. I have some of these just for when I do testing in my back garden; no long or challenging flights.

I tend to buy props marketed for the DJI Phantom 3 as they are plentiful and cheap. The H109s props are very expensive and the same size as the Phantom ones.