This is a big AMAZON goof! (not the fault of APC)
(so, on this product: APC is 5-STAR, AMAZON is 1-STAR)
This SC420I is an "International" model.
(that last character in "SC420I" is a capital letter "I" for "International")
The source voltage on this international unit is 220VAC-240VAC only.
So, the 110VAC-120VAC model is:
"APC Smart-UPS SC SC420 420VA 120V UPS System"
It's available right here direct from AMAZON and, as of this writing, is 50 USD less!
AMAZON needs to do at least three things regarding this and TONS of similar issues:
1. Provide a comprehensive, store-wide product rating system differentiating product quality
issues from those of shipping, vendor, AMAZON site I/F, etc. issues.
2. Exercise FAR more diligence in providing and maintaining accurate product
descriptions, tech specs, photos, etc.
3. Fix their VERY messy, duplicitous, inaccurate, illogical search engine / interface / data base(s).
AMAZON's Mr. JB needs to come in off the golf course, stop playing with his Kindle for a moment,
and apply a bit more biz & personal responsibility in this little billion-dollar, low-overhead,
easy-to-do-right, ethereal (can't see, can't touch) product market!