The 21700 rechargeable battery with electronic protection circuit from Trustfire is a price-performance winner in every respect . The industrial cells used for the construction of the rechargeable batteries mostly come from premium manufacturers located in the Asian region whereby the costs could be drastically reduced.
Very often in the past Trustfire batteries have been dragged into the bad light by plagiarism and name similar brands. Nevertheless, Trustfire kept its name and developed into a torch manufacturer that can compete with the big known manufacturers;

PCB/BMS protected Li-Ion 21700 battery from Trustfire.

Electronically (PCB) protected against over-voltage, under-voltage, short-circuit and reverse polarity. Applications: Torches, industry, LEDs and model making.

Please note the dimensions of the cell before buying! Due to the built-in electronics, the cell is not suitable for every application!
Height and diameter are larger than a standard 21700 cell without PCB.

Safety instructions:

Please note that lithium cells may only be used by competent persons.
Incorrect handling or short-circuiting may result in fire or explosion.

Further properties:

Lithium-ion batteries are thermally stable and are not subject to memory effect.
They work on the basis of lithium and are characterised by a high energy density.

Notes:

A special charger is required for charging lithium-ion batteries, which charges the batteries according to a special charging procedure. (CCCV = constant current, constant voltage.) The batteries must not be charged above a voltage of 4.2 volts, otherwise there is a risk of fire and explosion. It is advantageous to charge the batteries only up to approx. 4.1 volts, as this significantly increases the service life or the number of charging cycles (possibly up to double). Only lithium ion chargers may be used for charging. However, the cheap chargers sometimes have the disadvantage that they do not switch off safely at the end of the charging process, but continue to charge the batteries with a small charging current, which can be dangerous.

Furthermore, rechargeable batteries and batteries do not belong in household waste! Please dispose of them as prescribed by law at the municipal collection points or in the [usually green] containers provided by retailers.