6 LED Light has a 1-1/8" outside diameter.
Inside opening diameter: 1/2" Yes a 1/2" OD tubing will fit snugly in this hole.

12 LED Light: $19.67
12 LED Light has a 1-1/4" outside diameter
Inside opening diameter: 5/8" Yes a 5/8" OD tubing will fit snugly in this hole

For 6 & 12 LED Lights
Electrical Specs: AC-DC Adapter
Input 120V ~ 60Hz ~ Output: 12.0V ~~ 100ma
Electrical cord length from light to connection to transformer. 31'
Electrical cord from connection to transformer: 6'

24 LED Light: $28.47
24 LED Light has a 2-1/2" outside diameter
Inside opening diameter is 1-1/2"

24 LED Light Electrical Specs:

Input: 120VAC ~ 60Hz ~ 10VA
output: 12VAC ~ 0.5A ~ 6VA
Light's cord to connection: 31'
Watertight transformer.