a half rack is a 12 pack. at least that's what they called it when i lived near seattle

A "half-rack" is simply a form factor for audio equipment units. For example, you can have an effects unit that sits in a rack for protection, a "full-rack" is an effects unit (or amp, or whatever) is twice as thick as a "half-rack".

So if you can fit 4 full-rack units in a rack, then you can fit 8 or so half-rack units in that same rack (but leave room between the units for airflow).

Grant

Mice are in estrus for a period of about 10 to 12 hours, and they will go into estrus every 3 or 4 days.

Drink it.