They are the same as Sears 14911.
I do not know it came in the humidifier. If I remember correctly it was not in a box, but wrapped in plastic. However, I can say that humidor works beautifully and If I had to would buy it again.
Sorry but Do not find a listing for your # HD3120DCN on Aircare product sheet. Your best course of action would be to contact Aircare direct. Call; 1-800-547-3888
they are the same as sears 14911
Hi, Del. Thank you for the question. No, the filters HDC12 does not replace the HDC411 filters. Thanks! - Lisa, Essick Air Products
I am unsure those. The ones i have been using for years home depot sells is the HDC12 SUPERWICK . I have very hard water and will use 3 to 4 sets in a season.
Hi, Kris. Thank you for the question. Dimensions of the HDC12 wick are 6.25"(H), 8"(W) & 2.38"(D). Thank you. -Natalie, Essick Air Products
Yes, it does fit..
There is nothing in my use & care guide that gives other make or models that HDC12 wick will fit, sorry to say. No help on this end, sorry!
No, this is not specified to be compatible with your humidifier.