Sterilizing outfit for use with water bottles WW2

Square tin with rounded corners and hinged lid, the lid is painted brown with green lettering reading 'STERILIZING OUTFIT FOR USE WITH WATER BOTTLES - KEEP DRY', the inside of the tin lid is inscribed instructions for use, inside the tin are two bottles - one of brown glass and one clear, the brown glass bottle is labelled '50 THIO TABLETS' and the clear bottle is labelled '50 STERILISING TABLETS'.