The Sarov Mod by Vaperz Cloud can accept 18650, 20650, 20700 and 21700 batteries and does not require any adjusting or spacers or rings. It is built with a telescoping hybrid top section that will simply thread further down to make contact with shorter batteries and not thread as much for taller batteries. Regardless of what cell you are using there will be no gaps in the appearance and nothing to adjust.
The Sarov Mod also utilizes a newer version of the Comp-S switch where the contact is a true circle now to maximize consistent button throws and fires regardless of where you hit the button.
The Sarov Mod is 25mm at the top and is finished to be a perfect match for the Voras RDA.