A vaping device with adjustable output, a larger battery and a tank or pod designed for bigger vapour. “Mod” is a leftover from the days when people literally modified torches; today it just means the powerful, configurable end of the market, with all the safety handled by the chipset.
You set a wattage, the chip drives the coil at exactly that power, and the coil resistance determines the character: lower resistance and higher watts give warmer, denser vapour. Match the wattage to the range printed on your coil and use high-VG liquid, and a mod is no harder to run than a pod kit.
Yes, every kit here charges over USB-C. For dual-battery mods a standalone battery charger is still worth £15: it charges faster, balances the cells evenly and spares the device’s port. Never charge loose batteries unattended, and retire any cell with a torn wrap.
In hand luggage, yes; devices and batteries are banned from the hold on UK flights. Empty the tank before flying (cabin pressure forces liquid out), keep spare batteries in a plastic case or sleeve, and remember using it on board is illegal everywhere.
£21 gets you a genuinely good single-battery kit like the Nord 4, £30 to £35 covers the strong mid-field, and £50 to £55 buys flagship builds like the Aegis Legend 2 with dual batteries and full weatherproofing. Past that you are paying for finish, not function.