What size needles for emergency kit?

[Sonoran Silkies]

I am thinking about getting penicillin and tylan injectibles to keep on hand. What size needles would y'all recommend?

Are there other sizes needed for other meds?

 

[catwalk]

I think Marek's vaccine is given with a 20 ga? That may be too small for Pen, though. It's fairly viscous. I would think the shorter needles, too would give you more control over what you're doing.