Sling Media Slingbox User Manual page 11

The lightning flash with arrowhead symbol, within an equilateral triangle, is intended to alert the user to the presence of uninsulated
"dangerous voltage" within the product's enclosure that may be of sufficient magnitude to constitute a risk of electric shock to persons.
The exclamation point within an equilateral triangle is intended to alert the user to the presence of important operating and maintenance
(servicing) instructions in the literature accompanying the product.
WARNING
To reduce the risk of fire or electric shock, do not expose this product to rain or
moisture.
Note to CATV Installer
This reminder is provided to call the CATV system installer's attention to section
820-40 of the NEC, which provides guidelines for proper grounding and, in
particular, specifies that the cable ground shall be connected to the grounding
system of the building, as close to the point of cable entry as practical.
Slingbox User Guide
Important Safety Instructions
7