Nikon D6 Reference Manual page 51

Use Only Nikon Brand Electronic Accessories
●
Nikon cameras are designed to the highest standards and include
complex electronic circuitry. Only Nikon brand electronic accessories
(including lenses, chargers, batteries, AC adapters, and flash accessories)
certified by Nikon specifically for use with this Nikon digital camera are
engineered and proven to operate within the operational and safety
requirements of this electronic circuitry.
The use of non-Nikon electronic accessories could damage
the camera and may void your Nikon warranty. The use of
third-party rechargeable Li-ion batteries not bearing the
Nikon holographic seal shown at right could interfere with
normal operation of the camera or result in the batteries overheating,
igniting, rupturing, or leaking.
For more information about Nikon brand accessories, contact a local
authorized Nikon dealer.
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Notices