[Closed] Dainese Trail Skins elbows - how do they size up?

Thinking of getting some for both knees and elbows, but am a little unsure of the elbow sizing as I can't find a guide anywhere!

I tend to be a medium in most things, but am blessed with 'aristocratic' fingers and lower arms (read skinny) so would like to have an idea of what I'm ordering before pressing the button.

I've got some older Dainese 4X elbows and knees - the knees are fine, but I added extra velcro to the elbows to get the fastening to attach securely.

For the record, there's no Dainese dealers with them in stock locally, otherwise I would try on.