I found this on the original design/review for the Convoy L6
Update: 2016-05-14
Mixed message today. The positive is I received my L6 today and I love it. The negative is that it seems the recommended 5200mAh protected cells are too long. It’s my understanding that cells over 70mm will not fit this light. That still leaves several cell options, just not the recommended cell. The Convoy store listing will be updated once this is officially confirmed. Please order cells that are no longer than 70mm for the L6.
Update: 2016-05-16
Simon should be receiving the neutral emitters tomorrow so we should see the listing very soon.
The new neutral (5000K) emitter is an XHP70 N2-3A.
Good news on the recommended battery too. Apparently the new Keeppower 5200mAh protected cells are indeed under 70mm so it was not a mistake. Simon added a note to the L6 listing to help clarify this. If that is your cell of choice just confirm with the seller that it is the new version. The older version of that cell is too long at 71.1mm. Stick to cells under 70mm.
Specs on the King Kong 26700 Cells I have: https://web.archive.org/web/20160316193817/http://www.mtnelectronics.com/index.php?route=product/product&path=59&product_id=312
Length: 70.6mm