Help! ?How to size sais?

I'm fairly new, compared to most of you, to the MA's. I practice Isshinryu karate. I'm 5'8 and I'm wanting to know how to size a pair of sais. I've heard I need to judge by my forearm length, does this include my hand or no, the grip or just the blade? If I measure from the tip of my fingers to the fold in my arm is probably about 18 inches, but without my hand it obviously is quite a bit shorter (about 15 inches). And if you will be patient with me, what is the differance between octagonal and round? Or is it only preferance? Thanks in advance.

Go in peace and may the horse be with you.

Krazykuky

[This message has been edited by krazykuky (edited 03-22-2005).]

The length of the sai, grip and everything, should be a little longer than your forearm. When held comfortably in one hand, the sai should extend about 1 inch past your elbow. I'd say go for a sai that is around 19 inches(I apologize if this doesn't make sense, I'm not the best at explaining).I find that octagonal vs. round sais boils down to a personal preference; I haven't noticed a difference.

Thank you so, so much!

The difference in the octogan sai is that it will break bones more easily than the round ones. That little edge lets it penetrate better.