The Le Petit Gros is a 18350 with a hybrid adaptor. The atty actually sits about 1/2" inside the mod. On it is a Kayfun Lite base with a nano TT plasma tank.
The adaptor screws onto the atty and then you screw it onto the mod until it touches the button top.
*** WARNING *** IF the positive post of the 510 is flush or near-flush... or it's screwed down too tight and it dimples the battery top... it can cause a Dead Short and............. BAMB !!! its will blow up. That kid (Kat's neighbor) had his blow up....