From a brief search, it appears that Barstow uses a variety of lightbars on their vehicles. The one in the picture your posted is for sure a Whelen Liberrty, and what's more is that it looks like it's a custom build of some kind. It seems that the older units used Code3 X2100's, while the newer units use the Liberty's or clear-topped FedSig Legends. The newest units (Charger's) are using FedSig Valor bars.
Again, this is just what I've gathered from the few pictures I've been able to find through a quick Google search. Hope it helps!