I use the English flints. Basically because they're pretty abundant at Friendship and can be had for a good price. I had an old timer in the gunsmith shack harden both (I have a spare) my frizzens for me a couple years ago during the Spring Nationals. Made a huge difference in the spark category. I also tried a couple "Dura flints". I'm not sure if these things are even made anymore, but you talk about sparks and staying SHARP! If you ever get the chance to try one Loggy,,,you need to check 'em out.