Scale: 1/128.  This model "lantern" is 18 mm tall and 15 mm in diameter.  Please consult your model ship's plans to ensure that the size of this model is a good match.  Re-scaling to match your specific model's plans is possible, if desired.
 
Recommended for:
Fleetscale 1/128 scale King George V Class Battleship
Fleetscale 1/128 scale Nelson Class Battleship (HMS Nelson and HMS Rodney)
Fleetscale 1/128 scale Town Class Cruiser
Fleetscale 1/128 scale County Class Heavy Cruiser (Royal Navy / Royal Australian Navy)
Fleetscale 1/128 scale Queen Elizabeth Class Battleship (HMS Warspite)
Fleetscale 1/128 scale Royal Sovereign Class Battleship (modified Revenge / R class)
Fleetscale 1/128 scale H class Destroyer (Royal Navy / Hellenic Navy / Brazilian Navy / Argentine Navy / Polish Navy / Royal Canadian Navy / Dominican Navy / Royal Netherlands Navy)
Fleetscale 1/128 scale Colony Class Cruiser (Royal Navy / Royal Canadian Navy / Indian Navy / Peruvian Navy)
Fleetscale 1/128 scale Renown Class Battlecruiser (HMS Repulse and HMS Renown)
Fleetscale 1/128 scale Dido Class Light cruiser (Royal Navy / Royal New Zealand Navy / Pakistan Navy)
and more!
 
This 3D-printed product represents the protective perspex "lantern" housings for the exceptional Royal Navy Type 271 and Type 273 target indication radars. This feature is often missing from some plastic model kits and oversimplified in others.  This is the 16-faceted "round type".

On HMS Nelson and HMS Rodney, it was found on the mainmast starfish.  It is known to have been carried on the battlecruiser HMS Renown and some battleships of the King George V class, Queen Elizabeth class and "R" class.  This was also a common feature found on County class and Town class cruisers, Dido class light cruisers, and escorts including the famous Flower, Castle, Kingfisher and Banff class corvettes of the Royal Navy, Royal Canadian Navy and Royal Australian Navy. 

There were many varieties of perspex housing.  This design represents one of the most common kinds installed on major Royal Navy World War II combatants, the other being octagonal.  Consult your references to know if this lantern is suitable for your model ship.

© Model Monkey LLC.  This 3D-printed item may not be copied or recast.
 
From Wikipedia: "Type 271 was the original naval centimetric target indication radar, later fitted with a plan position indicator. Modifications P and Q were known as the "Centimetric Mark IV". It had separate transmit and receive aerials, small parabolic dishes stacked on top of each other, and referred to as "cheese" after their shape. The antenna array was carried in a distinctive protective perspex "lantern", and initially had to be fitted directly onto the radar office roof due to limitations in coaxial cabling (until suitable  waveguides  had been developed). The Type 271 was a vitally important war weapon, as for the first time it allowed escort ships to reliably detect surfaced U-boats or even just their periscopes. It was first fitted in HMS Orchis. 350 sets were ordered. It was fitted widely to escort vessels of corvette and frigate size.

"Type 273 "Centimetric Mark IV" target indication set. This set was based on the Type 271, but was intended for major warships of cruiser and battleship size. It used side-by-side 3 feet (910 mm) wide cheese antennas that were carried in a distinctive protective perspex "lantern". In the Battle of the North Cape, HMS Duke of York identified the target of Scharnhorst at 45,000 yards (41,000 m) using her Type 273 set."