The LA-T16 extension is only recommended for use in the following scenarios:
Powering the Lab 35 with 18500 batteries, or powering the Lab 50 with 18650 batteries.
Using the Evolv Kick 1/2.
The T16 extension has an internal diameter of 18.40mm, thus limiting the battery diameter to 18.30mm max, which means that some (usually low-quality) batteries with thick insulation may not be able to pass through it.
It is preferable that you use the T16 as a “new bottom cap” for your device. Keep the bottom cap mounted on the T16, and unscrew the T16 from the device. Insert your battery inside the device and then screw the T16 back on. Make any necessary micro-adjustments with the bottom cap, to ensure that the battery is held tight enough in place.