The above posts are good advise. For get wooden props!! They are expensive and the slightest touch against them when the engine is running and they will instantly snap in 2!!! For training the MAS props are the most strurdy and work just fine. You never said what size engine you have so I can suggest 11-5 prop for a 46 size engine and a 10-5 prop for a 40 or 42 size engine. [8D]