Helos E Nail Short Short eNail Increases diffusion and cooling Working voltage of 3.2V-4.2V Cut the cost with the HELOS short eNail. Made short for extra diffusion and vapor cooling, the short eNail is made with flawless threading. In just a few seconds, you can replace your old eNail by simply screwing it into the cartridge. The short eNail is made compatible with the original HELOS cartridge, HELOS-X and HELOS-G. Working voltage of 3.2V-4.2V