Protection class IP 68 according to DIN EN 60529 (VDE 0470)
(Citation of standards without guarantee)
The protection class of an object is defined by the IP (Ingress Protection) indicator and a two-digit code number behind it. The first digit indicates the degree of protection for persons and equipment, the second the degree of protection against water.
Thus with IP67:
First code number (protection against foreign bodies and contact):