Have a look at the data of Mitras Lightbar 140:

Mitras Lightbar 140
for tank 139 - 150 cm
max. power consumption: 82 W

-> the length of the lightbar itself is 131 cm; incl. cover, cables and holder it is 139 cm.
The holder can be extended up to 150 cm.

The tank size 139 - 150 cm is the inside dimension of a tank.

Hope this helps.