To check the batteries or battery tubes within an SDL, it may become necessary to remove the white SDL cap.
![P1040615](http://www.nexsens.com/wp-content/uploads/2013/09/P1040615.jpg)
Figure 1: Note the white SDL cap
Carefully unscrew the white cap going counter-clockwise.
![P1040616](http://www.nexsens.com/wp-content/uploads/2013/09/P1040616.jpg)
Figure 2: SDL Cap partially removed
With the cap removed, batteries may be replaced. Battery tubes can be checked and o-rings can also be inspected. Whenever the cap will be reattached to the SDL, be careful not to cross-thread while tightening it back on.
![P1040617](http://www.nexsens.com/wp-content/uploads/2013/09/P1040617.jpg)
Figure 3: White SDL cap removed. Inspect o-rings, check battery tubes or change batteries as needed.
REV: 13J06