The Eleaf iStick i40 is a compact regulated box mod designed for vapers who want precise variable wattage control in a pocketable, everyday device. A 2600mAh internal battery and 40W maximum output make it a capable choice across a wide range of tanks and vaping styles, from tight mouth-to-lung setups through to lower-power sub-ohm use, without the extra weight or bulk of a dual-battery device.

About the Eleaf iStick i40 Mod

The iStick series has been one of the most consistently popular mod ranges in the UK vaping market, and the i40 is a well-judged continuation of that line. Eleaf built it around a combination of polished metal frame and a leatherette grip panel, which gives the device both a premium feel and a secure hold. Despite the premium materials, the overall size stays compact at 34.8 x 25.2 x 77.6mm, making it genuinely pocketable for a full day out.

The 510 connector is standard thread, meaning it pairs with virtually any tank or atomiser on the UK market: clearomizers, MTL tanks, RTA builds, and sub-ohm tanks all connect without adapters. That compatibility is one of the things that keeps the iStick i40 a practical choice even as a secondary or backup device alongside something with a built-in tank.

Variable Wattage and Variable Voltage

Output on the iStick i40 runs from 1W to 40W in variable wattage mode, which covers the practical spread of use cases: 8 to 15W for MTL clearomizers and high-PG nic salts, 15 to 30W for restricted direct-lung tanks and 50/50 blends, and up to 40W for sub-ohm coils and higher-VG shortfills. Variable voltage mode is also available for vapers who prefer to control the output that way, giving an extra layer of control for users with specific builds or tanks.

SMART mode is included for less experienced vapers. It automatically sets the output based on the resistance of the coil fitted, removing the need to manually select a starting wattage when dropping in a new tank.

Battery and Charging

The 2600mAh internal battery delivers a comfortable full day of use at moderate wattages for most vapers. Charging is via USB-C at 5V/1A. The OLED display shows battery level, coil resistance, and current wattage or voltage clearly and without clutter. There is no touchscreen and no complicated menu structure: up and down buttons adjust wattage, and the fire button doubles as the mode selector through a simple click sequence. To lock or unlock the wattage adjustment, hold the two adjustment buttons together.

Available Colours

Available at Southampton Vaping Centre in Black, Cyan, Fuchsia Pink and Neon Orange.

Specifications

• Battery: 2600mAh internal

• Output: 1 to 40W variable wattage; variable voltage mode also available

• Connector: Standard 510 thread

• Display: OLED

• Charging: USB-C, 5V/1A

• Dimensions: 34.8 x 25.2 x 77.6mm

• Safety: Short circuit, reverse polarity, over-temperature protection

• Modes: Variable wattage, variable voltage, SMART

What's in the Box

• 1 x Eleaf iStick i40 Mod

• 1 x USB-C charging cable

• 1 x User manual

• 1 x Warranty card

What to Pair It With

The iStick i40 works well with any 510-thread MTL or sub-ohm tank. For MTL vaping with nic salts, a slim clearomizer or pod-style tank at 10 to 15W is the most popular pairing. For a slightly more open draw with shortfill e-liquids, a restricted direct-lung tank at 20 to 30W suits the battery life well. The leatherette panel and compact frame make it a practical carry for vapers who want a step up from a built-in-coil pod kit without moving to a larger mod.