Hoop: The height of just the front panel on the KPA1500 is 4 1/2" so looking at pictures of the K4 I am presuming the K4 has the same measurements as the KPA1500, that way the K4 sitting next to the KPA1500 they both would be perfect in height, much the same as the K3 and the P3 and the KPA500 -- *73 De Mike* *VE3YF _/http://www.ve3yf.com/_*