Do I need to wire in a relay to the inverter I wanna install?

[guccimane]

so I was looking at DC-AC inverters on Amazon (thinking of buying

this Cobra 400W AC inverter with USB ports

this Cobra 400W AC inverter with USB ports

) and the prices aren't that bad at all, like $20-50 for the most part for the regular, non-pure sine wave ones, but anyways I think I wanna go ahead and get one for my car, BUT do I need a relay for it?

I was looking around at different car audio and electrical sites like Parts-Express and I saw that some people use relays for sound and security installations, but would I need one to install an inverter?

for what it's worth, I was planning on wiring the inverter to a switch

like this illuminated rocker/paddle switch

like this illuminated rocker/paddle switch

so the inverter can be completely shut off from the battery so as to not potentially drain the battery when the inverter isn't in use (I know the inverter has a switch itself but I was reading around and it looks like it'll still draw from the battery a bit and I don't want to come back to a dead car lol).

anyways if y'all could let me know if I need a relay or not I'd appreciate it!!! by the way, would it also make sense to pick up a fuse holder to put in as well so in case there's a short?

Thanks y'all!