Frigates are cheap, easy-to-make ships that are a tier below destoryers and a tier above fighters.
An Earth frigate is 200m long, 50m wide, and has a crew of 20. They are only two full decks, with the dropship bay (ship not included) on the bottom. They are moved with Ion drives, and powered by single-gigawatt reactors.
They are armed with 75mm howitzers, 10 on each side, and a point-defence laser system.
Second deck is the MAC barrel and crew quarters, first is engineering, mainframe and storage. The howitzers are located on deck 2. They are armoured with 1m of composite plating.
They only have a standard mainframe, and cannot support an AI. In wartimes, these would be mass-produced, as they deal the most damage/crew count of any ship that isn't a flagship.