Where is this stated? We fly with Einsteins, Profoto, etc all the time, and TSA leaves their little paper pamphlet inside the cases every flight. Never a problem... And yes, the Einstein's are the lithium batteries.
According to the Elinchrom site under 100WH you can check them mounted in the equipment.http://www.elinchrom.com/support_downloads.php
Thanks folks.I'm in Canada and fly to Mexico and the Caribbean on jobs often. This limits me to our three domestic airlines that fly these routes. On the booking page of each of them I have to tick the "I agree" button that puts lithium batteries in the same category as dangerous cargo and prohibits them in the hold.