Thank you for taking the time to contact Sears.
What do you mean by a half box spring...what dimensions are you looking for?
There are several sizes in this set, the dimensions are approximate, in inches
twin 75(Length) 39(Width)
twin xl 80(Length) 39(Width)
double 75(Length) 54(Width)
double xl 80(Length) 54(Width)
queen 80(Length) 60(Width)
king 80(Length) 39(Width) (need 2 of these to fit with a king mattress)
Date published: 2015-02-02