I have the SP-31, and you’re right, it’s a nice tube light. The one thing I really like about it is the low voltage warning. Like you said, flashes at 3v which you can click to turn off and keep using the light. Then at 2.8v it flashes then shuts off, but you can click again to continue using the light. Kind of nice in case you were in a situation where you absolutely needed some light. Better to kill a battery than be in trouble with no light source.