A:Answer The bluetooth keyboard case should be able to connect to any tablet via bluetooth communications. However they are designed to fit specific models into them, because the unit is molded according to each respective device size & cut-outs. The TAB 3 may or may not fit on the TAB 4 , depending on the size. If the Tab 3 is a little smaller than TAB 4, then it should fit inside the case but will not be secure, since the case may be slightly bigger in size.