Mine shipped with a 3/4" square, amber flint installed upside down. It hit 1/3 of the way UP from the bottom of the frizzen at almost 90⁰ and promptly broke. Jaden was either out of the correct size or needs to spend fifteen minutes out back with someone who has some real trigger time with these products.
I knap my own so can make any flint size, shape, or thickness needed. Standard 7/8"x1" with a leather made from 6-7 ounce top grain cow hide, skivved thin on top and very thin at the fold to elevate the flint slightly in the jaws, hits about 2/3 the way up the frizzen at about a 30⁰ angle and ends up pointing dead center of the pan at rest and about 1/16" above the touch hole. It is also about 5/16" away from the face of the closed frizzen at half cock. Absolutely perfect.