We all know that to work on your time and tempo, a good metronome is kind of a key piece of gear to have in your bag. When working out your parts, it will ensure that you're learning them in the proper tempo, too. I prefer a classic wind-up mechanical one like this to the grating synthetic "beep" of one of those cheap electronic ones - and this one never runs out of batteries, because it doesn't use 'em!
A very tech-looking bit of kit, this thing is ultra small - the manufacturer claims that is' the smallest pendulum, spring-wound metronome in the world! And I believe it. The precision mechanical clockworks are made in Germany, and built into a very clean-looking ruby-colored plastic case. It comes complete with a clear plastic cover that protects the arm from being damaged in your gig bag, purse or coat pocket.
Did I mention that this thing is only 4" tall? It has a removable winding key that screws into the shaft for security (so you don't lose it).
This metronome is 100% mechanical; it winds up and requires no batteries. It is capable of supplying accurate timing from 40-208 BPM. Instructions included. Dimensions: 4"H x 1-1/8"W x 1-7/8"D
TL;DR: Highly accurate, highly portable, super cool metronome for players on the go.
Need to figure out some of the more in-depth features of this product? Here's a copy of the manual, in PDF format, here.
You may wish to visit the manufacturer's website to see if a more recent version is available.