Workman DL100W CB Radio Antenna 100 Watt Dummy Load
 
Used in place of an antenna to aid in testing a radio transmitter.  So that the transmitter does not interfere with other radio transmitters during the adjustments If a transmitter is tested without a load- such as an antenna or a dummy load- the transmitter could be damaged.
Also- if a transmitter is adjusted without a load- it will operate differently than with the load- and the adjustments may be incorrect. 

This dummy load is designed to operate in the HF band +/- 1Mhz ~ 30 Mhz
Power Handling 100 Watts
Connector UHF (also known as Female PL259 or SO239)
Impedance 50 Ohm
Workman Model: DL100W