The amPlug 3 is the third-generation in the series of headphone amps by VOX. 
The “UK Drive” model (model code AP3UD) emulates a UK-100 W-amp stack sound: 
Dual-channel, built-in stereo effects and rhythm machine (9 patterns) allow for richer practice sessions. 
Plug-in headphone jack + AUX input (for connecting smartphone) so the guitarist can play along with songs. 
Very compact: dimensions ~87×33×39 mm, weight ~40 g (excluding batteries). 
Power via 2 × AAA batteries (alkaline or Ni-MH) — good portability.