The latter...make sure the mask is tempered glass.
Don't be surprised if the other divers near you are moving much faster with much less effort - the fins are probably too short/stiff to properly propel a fully loaded scuba dive w/o making you work too hard. My friends husband only snorkels while we dive - I tried his (expensive) snorkel fins once - felt like I was diving in molasses.
US Divers 20 years ago was reputable - now they're the snorkel division of one of the dive mfr's - I think Aqualung.
Return it or use it for snorkeling...
You probably can't get what you got for $30 - more like $70-80 for serviceable gear.
Buy the low end dive gear at Leisurepro.com. Blue Reef is their house brand - some of the snorkels are $12-15. Cressi's - one of the original dive gear mfr's - under $20.
A decent serviceable paddle fin like Tusa's Liberatpr X10 are $40. They've been around for decades.
I bought the Sherwood version of this $30 mask a few years ago - it seals better than my $90 Mares.
Genesis LVX Two Window Mask
I really wouldn't buy a mask unless you can try it on and make sure it seals correctly. There must be 20 or 30 under $30 dive masks also - maybe more.
My snorkels dry rot b4 they get used so let that be your guide in buying one. I have one somewhere - bought ti snorkel with Whalesharks in 2007? - haven't seen it since.