Just wondering if anyone knows anything about thes...

Will it do the job for 5 plants

That's were I get my products from, that light has been around for a number of years I think. They used to have it in the store on show and whatever they grew under it always looked really healthy. For free you have got a bargain.

Got it for free is it worth using or do the job

Unless it is a matter of availability, that's a very overpriced LED. I hate to cause buyer's remorse, but thats fairly old tech that you probably need 50w/sq ft and definitely not worth 0. if you are looking to spend 600, check out a mars FC4800 or fc6500... moth would be significant upgrades. with those lights, you only need 20-25w/sq ft for autos and 30w / sq ft for 12/12 bloom of photoperiods. You can see the efficacy difference would save a ot of electricity comparing equal outputs (which is not the case here, but the mars lights listed here are 3-5x more powerful an FC3000 would cover more area and have teh same efficacy of the larger lights as well as much cheaper.... this would be a closer equivalent to that lamp. That is a 200w light (16 modules x 12watts each) and teh FC 3000 is 300w and much more efficient... it will cover the footprint promised by the h-16 you pictured, the h16 will not do as well. "eu countries" - https://www.mars-hydro.com/fc-3000-samsung-lm301b-led-grow-light 346 spider farmer is another with good bar-style lights like the fc 3000 but are not as efficient.. at same watts will give a little less light. if price is right, these differences are fairly small, fwiw. (samsung lm301 / lm351 diode led only -- divide watts by diode count, 0.25w/diode is how they are tested. anything over that decreases longevity and efficacy) the lm 301 is the most efficientn white diode onmarket.. but if the light drives them too hard with too many watts, they aren't so good long-term. midrange lights will be 0.40-0.50 watts per diode, to give perspective... 'top' will be 0.25w/diode. after that it's just a matter of a decent heatsink and a good driver... that's all it takes for a qualite LED light.