The MFJ-260CN is an air cooled, non-inductive resistor in a perforated metal housing. It has "N" connectors. You can handle a full load for 30 seconds. Silk-screened derating curve to 5 minutes. Handles 300 Watts. SWR below 1.1:1 to 30MHz,
1.5:1 from 30 to 650Mhz. It measures a super compact 2-1/4" x 2-1/4" x 7".

Specifications
IMPEDANCE : 50 Ohms, +/- 10 %
VSWR : Max: 1.3:1, 0-650 MHz
POWER : 300 Watts for 30 seconds
DISSIPATION : (2 min cooldown) 25 Watts continuous
DIMENSIONS : 2-1/4" x 2-1/4" x 7"