The MFJ-260C is an air cooled, non-inductive resistor in a perforated metal housing. It has SO-239 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 30 MHz, 1.5:1 from 30 to 650Mhz. It measures a super compact 2 1/4x2 1/4x7 inches.

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: 2½" x 2½" x 7"