The Canadian C 4 mask is an improvement of the British / Canadian Lightweight Service Mk III / C3 respirators, issued after WW II 

It is made of shaped olive drab or black moulded rubber. 

A curious bubble shaped plastic eyepieces equip the mask. 

The 40 mm NATO dia filter is directly screwed either on the left or right side of the mask.  

Two front casings include the exhale valve under the chin and a voicemiter in front of the mask.  

An inside half mask allows the de-fogging of the eyepieces and a drinking device completes the mask. 

The six points head harness is composed of short adjusting straps sewed on a net covering the head. 

The mask is transported in a bag worn against the thigh.

The Canadian C 3 mask is an improvement of the British Lightweight Service Mk I respirator first issued in 1940 and the followed models. 

It is made of shaped black moulded rubber. The 60 mm dia threading filter is directly screwed on the left side cheek of the mask .A large front casing includes the exhale valve and allow to work as a voicemiter. 

A special connecting fitting must be provided to allow to equip the mask with NATO 40 mm dia. filters in place of the standard British ones. 

As on all British / Canadian WW II and near post war masks the Triplex eyepieces are screwed in a large rings tightened on the masks by means of wires located inside of the mask.          

           A six points head harness made of elasticized  
           straps complete the mask.  

The mask is transported in a bag worn against the thigh.