The MFJ-264 dry dummy load will handle from QRP up to 1500 watts for ten seconds, or 100 watts for ten minutes.
50 Ohms. SO-239 input.
Cool down period must be 10 to 20 teimes the load usage.
SWR is better than 1.3 : 1 up to 650 MHz. It has a strong lightweight aluminum construction. 3 x 3 x 9 inches