There are five kits:
Standard Kit: AK-47, Glock-19, 2x Frag Grenade. (full chainmail)
Light-Fire Kit: Scar-L, Uzi, 3x Frag Grenade, 2x Stun Grenade. (full chainmail)
Heavy-Fire Kit: Scar-H, Tokyo-90, 1x Frag Grenade. (leather - no helmet)
Rapid-Fire Kit: M134, Glock-18C. (iron - no helmet)
Sniper Kit: AWM, Colt, Cobra, 2x Stun Grenade. (full iron)
To open the kit GUI you need to use the command: /kit <target>, there is also a kit item located in the combat tab that opens the GUI when right clicked with.
If you find that any of the kits are unbalanced (or have any other feedback!) please comment below!