ShL-61 series of helmets started to roll out from production line in 1961 and was a further upgrade of the original ShL-50 series of helmets. It is possible that originally ShL-61 was a simple upgrade from ShL-50 that only featured new mask hooks on sides, on top and on the bottom of the helmet. But since at the same time Soviet designers decided to use this helmet as a liner helmet for the ZSh-3 shell, a pad on top of the helmet was introduced. This is my version of how this helmet was developed, but it is entirely possible that helmet was from ground up designed to be used with ZSh-3 helmet and oxygen mask hooks were simply put there to accommodate newer masks.

As noted above, main difference between ShL-50 and ShL-61 is the pad on top of the helmet. Another noticeable feature is the new hook on the top adjustment strap on the helmet. It was to be used with newer oxygen masks.

Just like the ShL-50 series, ShL-61 was also produced in winter (ShZ-61) and tropical (ShLO-61) versions.

 

Right view of the ShL-61. Note the pad on top and mask hook on the rubber cover of the earphone.
Close up on the mask attachment hook.
View from above - pad goes over the strap.
New mask hook on front top of the helmet.
ID tag of the ShL-61 helmet. Just as with ShL-50, it does not show name of the helmet, but gives year of production (end of first green line - 1972 for this helmet). Number "57" in violet ink is the size of this helmet.
Front view on the possible fighter outfit of early 1960s, before ZSh-3 became widespread. It consists of the ShL-61 helmet, PO-1M goggles, KM-16 oxygen mask and La-5 microphone.
Same setup as above. It is possible bomber crews also used it.
ShLO-61 helmet - note the mesh top.
ShLO-61 helmet from the back.
ShLO-61 communication plugs. Note the small connector - regular La-5 throat microphones cannot be pluged in it.
Helicopter or early jet pilot outfit. It consists of ShLO-61 leather helmet, KM-32AG oxygen mask and PO-1M pilot goggles.