Only way for me is to buy it and put it in my mouth and try it...I have found that I can't use the ones made for people with a smaller mouth...I also don't like ones with real thin latex...

The ones that I usually buy are Quaker Boy or HS Strutt...I've had good luck with the Old Boss Hen...

I put mine in my basement fridge between seasons and also soak in mouthwash before and after the season to keep them fresh...