The SSV66 series of float switches provide high, low or high and low level monitoring for 45 gallon drums, these float switches do not require access to the inside of the drum as they can be fitted from the outside of the drum through the 3/4" NPT bung hole.

Suitable for a 45 Gallon drum hi/lo level switching
External mount via 3/4" NPT
N/O or N/C switching action
Fits standard 3/4" NPT bung holes
Flying lead or 4 pin M12 connection

The Cable entry point must NOT under any circumstances be submerged.
On the Horizontal switches they must be fitted through the wall of a tank so that the cable is on the outside.
On the vertical type the mounting thread and cable entry must be above the highest level of the liquid.