well how can i actually count its mm?i mean i cant really use anything inside the laser battery compartmant for that lol 33.5*16*16mm so the seller gave this mm on ebay for that kinda batter i guess both efset and keepower are bigger..any ideaas where i can get battery that has this size 33.5*16*16mm I think laser can handle more width it has room for it i can see the gaps so i dont think width is an issue as for length i dont really have any idea about that laser on off button is on its back i guess if the batter is larger and it pushed the button laser may turn on and off constantly as there is pressure on it?not sure but i think there is enough space for length aswell there is spring in there u were right..The Illumination Supply web site says the dimensions are 16.70 mm (D) x 35.60mm (L) so as GSS said above is a little bit longer.
It is little fatter by 0.7mm and 1.6mm longer making is a 356 instead of 340 because of the protection circuit and button top.
Nobody knows what laser you have but should be OK in most applications where exact 34.0mm length is not critical.
You can check you laser's battery compartment ---measure the length of batteries you have put them in the laser and see if you have room for 2 that are 35.6mm long. Usually exact length is not that critical as a spring contact at either or both ends will have that much play and if not then choose a different 16340.