Product Review

Ti4 Specification: 

LED: Cree XP-G2 LED with a lifespan of 20+ years of run time 
Mode & Runtime (Tested with 2*Ni-MH/900mAh):

Firefly(0.3 lumens, 137hours),
Low (24 lumens, 12hours),
High (252 lumens, 51minutes),
Strobe (252 lumens, 90 minutes) 

Working voltage: 0.9-3 V 
Battery: 2xAAA Batteries(not included) 
Peak Beam Intensity: 1120 cd 
Beam Distance: 67 m 
Waterproof: IPX-8 
Impact Resistance: 2 m 
Material: Aircraft grade aluminum body structure with premium type III hard anodized anti-abrasive finish 
Weight: 22.3 g (without battery) 
Dimension: 130 x 15 mm
  Accessories: 2x spare o-ring.

Operation

Battery Installation:
  Unscrew the light head, insert the batteries with the negative terminal down into the battery tube and then screw the light head back on.
 
  Turn on /off: 
Single press the tail switch to turn the light on/off.
 
  Change modes:
When the light is on, half press the tail switch (without hearing the "click" sound) to cycle through Firefly, Low, High, Firefly, Low, High, and Strobe. 
  When the light is on, quick double click (within 1 second) the tail switch to cycle through Firefly, Low, High, Firefly, Low, High, and Strobe. 
  If the second click is after 1 second but less than 10 seconds, the light will memorize the last mode. If it is after 10 seconds, the light will start from Firefly mode again. 
 
  Short Memory function
The light will turn on in the last mode accessed within a 1-10 seconds interval, except for Strobe.