New Project MAC Valve

Hi i have a question regarding circuitry.

I have a MAC Valve that has a 5V 5W operating voltage.

what can i use to drop a 7.4 LIPO voltage to a clean 5v source and what type of

switch (MOSFET or something like it, smaller is better) can i use to activate it

on and off with an arduino. it woud b great to find out what type of suprection diod to use as well

after the solonid. Its for a Airsoft marker. im having trouble

designing a fire controller unit as i am no electronic Eng. just a machinist

who messes around with an Arduino.

thank you for all your help guys and gals.