CustomDUO modules

Simple (r01)  discontinued

Now Available

Latest v42 (r02) and Simple (r02)

As the name suggests, the Simple (r01) is a no frills version of our popular v42 module, for the Petzl Duo. Well suited to those who like the operation of their caving lamp to be really straight forward, yet practical. Light output up to 430 lumen, seperate low power side LED and battery charge indication. 


sale £35  (was £55)

Simple (r01) Specification 

  • Will work with any original pre 2018 Petzl Duo - the Cavers Duo!
  • 3 regulated light settings; low, medium and high, 430 lumen maximum output
  • Forward bias flood optic, for optimal use of light output for caving
  • Latest high power XP-G3 LEDs (172 lumen @ 350mA @ 85 degC) 5000k neutral cool tint
  • Also available with 3000k warm XP-G3 LEDs (156 lumen @ 350mA @ 85 degC)
  • Seprate low power side LED (8 lumen), and battery charge indication 
  • Super robust, proven circuit architecture
  • New alloy PCB with custom heat sink, and discreet thermal management
  • Simple push fit directly into existing Petzl Duo pilot bulb connection, see Fitting Guide 
  • No power drain on batteries when lamp is switched off
  • Progressive dimming at end of battery charge (will not just shut off when batteries are flat)
  • 6.0 volt maximum input (4x AA batteries)

The Simple has three power settings (see following table). To switch between the settings, use the down switch on the Petzl Duo. Switch on-off-on-off etc, to move between settings 1-2-3 ... 1-2 etc, in a looping sequence. Setting 1 (low) will blink momentarily when selected to make it very easy to determine where you are in the sequence, and which setting has been selected. 



LED level


(5000k LEDs)


(3000k LEDs)


(est. 2500mAh eneloops)




73 lumen

65 lumens

16 hours




172 lumen

156 lumen

6 hours




430 lumen

390 lumen

2+ hours


side LED


8 lumen

8 lumen

includes battery
level indicator

* estimated light output at 85 degC dependant on capability of batteries used

Operating the switch very quickly, on-off-on ('double switch') will turn on low power side LED. At this point, the main LED will blink 1 to 5 times to indicate the approximate level of battery charge.  

The Simple features a 3 second 'first' mode memory. When lamp has been on for more than 3 seconds in any setting and is switched off, then it will automatically restart at the first setting (low) when next switched on. 


The Simple constantly monitors temperature. If the module is too hot, it will automatically step the power down to a lower level of light in order to protect the LED, and remain at this level until next switch operation.


The Simple has zero battery consumption when switched off, so there is no requirement to disconnect batteries. However it is probably best practice to do so when not in use for more than a few days, to reduce any stress on battery contacts in Duo box.