Oerlikon 35-mm Twin Gun, New Brunswick Military History Museum, CFB Gagetown, New Brunswick. The Oerlikon 35 mm twin cannon is a pair of towed anti-aircraft guns made by Oerlikon Contraves (renamed as Rheinmetall Air Defence AG following the merger with Rheinmetall in 2009). The system could be paired with the off-gun Skyguard fire control radar system. Canada had 20 GDF-005 units and 10 Skyguard FC radars which have been phased out.