I think type f & g are the highest class 1 pulse lasers you can buy, same goes for burst lasers. class 1 beam lasers go up to type e I think. To get higher types you need a higher class weapon slot. I.e bigger ship.
Also check the icon type in the box, a crosshairs means fixed lasers, two ovals means gimballed and turret means what it says.
Gimballed lasers have slightly less power than fixed lasers of the same class.
Oh and always check the power requirements when buying new weapons, otherwise you will find that you may lose power to half your ship when you deploy hard points.