WWII Bulgarian Luftschutz "gladiator" ID?

[Lubo]

H guys, I've recently got this one, they are not rare, but this one is in 100% untouched and most importantly undamaged condition!
Please, help me identify the maker and/or the year of this batch!
Thank You in advance!

[Lubo]

Please, excuse the sideways pictures, my IPad doesn't want to play by the rules
The stamp is saying:

L.239/25

[Donald L.]

//

Manufacturer is ET-Thale,

Don

[Lubo]

Thank You!
Does it tell the year of manufacture?

[Donald L.]

/

No, the number will not indicate the year of Mfg. The RL2-39/25 is the unique identifier number issued by Reich Ministry for Luftschutz indicating that ET produced a one-piece Luftschutzhelm that was approved by the ministry. Essentially the design had been tested, passed and was approved for distribution by the governing Reich office.

Don