For Self Contained Fountain Tower

No tools needed for assembly, 

replace batteries (4 D Cell) by turning the rotor-style nob on top of battery compartment

4 1/2" diameter

Battery service life, the below results in 2019 were using Duracell D size Alkaline batteries:

1 hour each day: 93 days / 93hours

2 hour each day: 44 days / 88 hours

3 hour each day: 29 days / 87 hours

4 hour each day: 22 days/ 88 hours