I should have looked at the photos more closely--these are actually 3 inches deep and 4 inches wide.  The measurements listed by Wayfair are transposed as of 2018-07.  I'm not sure if I'll be keeping these.  I haven't tried hanging them on my wall since I'm not certain they'll fit my depth requirements.  

Wayfair product listers: attention to detail matters.  Please do better.