Your Warranty is safe as long as you follow our Thumbstick Compatibility guidelines:
PuK Thumbstick Compatibility Guide
The Puk Thumbstick is compatible with all slate form factor mobile devices with a hard glass display. This includes most phones and tablets but folding phones with soft displays are not compatible. These soft displays do not allow for ideal smooth motion of the Thumbstick and we cannot guarantee that soft displays will not be damaged after extended use.
The magnets used in PuK products are not strong enough to cause permanent damage to your mobile device, but they might cause temporary disruption to some functions such as GPS, but only while attached to your device.
You can view our Magnet safety data sheet here: Magnet Safety
The PuK Thumbstick doesn't require any permanent modifications to your device.