eBay

Highly visual liquid crystal pendulum
13 different rhythms are built-in so you can practice to more than a click track
Rhythms include duplets, triplets, triplets with inner beats omitted, quadruplets, and quadruplets with inner beats omitted
Twelve reference pitches C4 -B4 for you to tune to
Adjustable calibration (438-445 Hz)

Specifications

Tempo Range: = 40–208/minute (BPM)
Beats: 0–7 beats, duplets, triplets, triplets with middle beat omitted,
quadruplets, quadruplets with middle beats omitted
Tempo precision: +/-0.2 %
Reference tones: C4–B4 (C, C♯, D, E♭, E, F, F♯, G, G♯, A, B♭, B)
Calibration Range: 413 Hz–420 Hz, 438 Hz–445 Hz (1 Hz steps)
Reference pitch precision: +/-1 cent or better

Connector: 1/8" mini-jack
Speaker: Dynamic speaker (28 mm diameter)
Power supply: Two AAA batteries, 3V (included)
Battery life: Approximately 250 hours (tempo 120, time 4, using zinc-carbon batteries)
Dimensions (W x D x H): 104 x 64 x 15 mm / 4.09 x 2.52 x 0.59 inches
Weight: 57 g / 0.13 lbs. (without batteries), 79 g / 0.17 lbs. (including batteries)