The built-in 650 mAh can be charged through a micro USB port at the bottom of the device and lasts roughly 400 to 500 puffs. There is a three color LED indicator on the device that shows the battery level of the device: green light for 4.2 to 3.85V, orange light for 3.85 to 3.55V, and red light for 3.55 or less.
The UPEN can be filled up to 1.5ml with salt based nicotine E-Liquid through a convenient threaded top fill cap. This MTL device with a non-adjustable 1mm dual slotted airflow paired with a 10mm bore drip tip. The UPEN utilizes the Digiflavor Nano Ni80 MTL coil head that has a resistance of 1.2ohm. The device is made of a combination of Stainless Steel and Zinc Alloy.
The pen-style cap included not only keeps the device clean, but also helps maintain the UPEN's discreet and classy look. The Digiflavor UPEN is excellent for users looking for a sleek, yet low profile MTL device.