Exhaust crush washers - which way 'round?

I've got a pair of Commando crush washers to use with my new 750-style pipes. My 850 had collets, so no old washers to observe on removal. The washers have a flat side, and a rounded (convex curve) side - which side goes in/out?

Thanks all - BrianK

I always fit mine 'flat-side' into the head - curved side against the exhaust.

Thanks Mark - BrianK