small 1.5" speaker box/horn

transmission line horn fits 1.5 inch speakers like this. https://www.amazon.com/Range-Speaker-Stereo-Woofer-Loudspeaker/dp/B01KFUIK88/ref=sr_1_5?ie=UTF8&qid=1473252296&sr=8-5&keywords=1.5+inch+speaker Keep in mind they must be glued in. I would also recommend taking a cotton ball and pull it in a 3x1.5 inch sheet and stuffing that in the channel to slow out going sound for more bass. Make sure you do it before you glue the top on.