Topband: LIGHTNING PROTECTOR

[Mr Magoo]

A pair of government surplus Polyphase IS-50 protectors came my way recently 
and I'd like to use them on my 160M verticals to replace what I currently 
use.  They are exactly alike in appearance to the IS-B50LU and similar, but 
a test reveals they have DC continuity.  I can find nothing in  Polyphaser's 
web page about a non-DC blocked device for a transmit antenna and carrying 
this part number.

Has anyone ever run across units like this, or are these in fact faulty?

Bill VE3CSK