The IP rating indicates the level of protection a product has against the entry of solids and liquids. It is expressed as IP XX.
The first number indicates protection against solid objects. The second number indicates protection against liquids.

Protection against solid objects

X = Not measured
0 = Not protected
1 = Protected against solids ≥ 50 mm in diameter
2 = Protected against solids ≥ 12.5 mm in diameter
3 = Protected against solids ≥ 2.5 mm in diameter
4 = Protected against solids ≥ 1 mm in diameter
5 = Protected against dust (limited ingress, no harmful deposits)
6 = Completely protected against dust

Protection against liquids

X = Not measured
0 = Not protected
1 = Protected against vertically falling water drops
2 = Protected against water drops (15° from vertical)
3 = Protected against rain (60° from vertical)
4 = Protected against sprayed water
5 = Protected against jets of water
6 = Protected against forceful hose-projected water
7 = temporary immersion (-1 meter for 30 minutes)
8 = prolonged immersion (deeper than 1 meter for period defined by manufacturer)

Petzl headlamps fall into two categories:

Water resistant = IPX4 or IPX6

These Petzl headlamps withstand the worst weather conditions: high humidity, snow, torrential rain, sudden immersion, etc.
They work even when water enters the lamp body. Thanks to stainless steel contacts and waterproof parts that protect sensitive parts.
If water enters the headlamp, it should be dried and the batteries changed. The contacts should be inspected. This applies to all headlamps, except for the e+LITE, the SiGNAL and the DUO line.

Waterproof -1 m and -5 m = IPX8

Some Petzl headlamps are waterproof.
They can withstand an immersion of more than 30 minutes at -1 m to -5 m. If water does enter the headlamp, while changing the batteries in a damp environment, it should be dried.
This applies to the e+LITE, the SiGNAL and the DUO line.
Please note: to maintain the waterproof properties of a headlamp, certain care and storage guidelines must be followed.
Note: If sea-water gets inside, rinse the lamp thoroughly in fresh water and dry it.

Electromagnetic compatibility

All Petzl headlamps conform to the requirements of the 89/366/CEE directive concerning electromagnetic compatibility: they will not interfere with any other CE-marked devices.