This value indicates whether and to what degree is a lamp against the ingress of water managed. The FL1 Standard distinctively in 3 different categories:
The test object is exposed to splash water from different directions at a certain pressure for a predetermined time, and this must be unscathed.
Water resistant (IPX7)
The test object must immerse in a water depth of one meter over a period of 30mins unscathed.
The test object must emerge unscathed from a specified by the manufacturer of water depth (at least 1 meter) over a period of 4h.