These are similar to a hyperdrive, but with one significant difference: a transit generator shifts a ship into hyperspace and then…leaves it there. You will need to use the transit generator again to drop back to normal space.

A universe where transit generators are the standard for FTL travel assumes that hyperspace can be navigated like real space, using your starship's normal propulsion. Or it assumes that hyperspace has “currents”, that carry your ship along with it, without need for propulsion.

Transit generators are smaller than hyperdrives, for the simple reason that they don't provide any hyper thrust on their own. A generator can transit one tonne of ship for every 2kg of generator—so your transit generators will occupy 2% of the ship's total mass. They occupy one cubic meter per every 750 tonnes it can transit, but this space requirement is halved if the generator is located entirely externally. Mind you, external transit generators like this cannot be worked on from inside the ship. You have to land the ship, or go EVA, in order to fix it.

Transit generators are rather expensive, at ₠400 per tonne of ship to which they are fitted.

Transit generator require power only upon activation, to enter or to leave hyperspace. They will burn 320 kilowatt-seconds for every tonne of ship that they transit, but no power once transit has been made.

If you'd rather use an exotic hyperspace fuel, 5 kilograms of fuel will transit one tonne of starship, either up or down.

The standard of two parsecs per week is a good starting point for transit drives. However, this assumes that your ships have some reasonable means of getting around hyperspace. Your Game Master will let you know if there are considerations surrounding that.

In many settings, “bands” of hyperspace that allow higher speeds exist. A hyperdrive that can access such higher bands may have proportionally higher mass, power or fuel requirements. Alternately, one of those factors might be increased by the square of the increase in speed. This is seen in David Weber's Honorverse; four times as much power is needed to access the Beta band, nine times as much to access the Gamma band, and so on.