The Voice Amplifier ST2-SR is a communication accessory for the Sundström SR 100 / SR 90-3 / SR 900 half mask Air Purifying Respirator (APR) and SR 200 full face mask Air Purifying Respirator (APR).

The microphone is mounted onto the exhalation valve seat of the respirator. The pocket-size loudspeaker can be clipped onto a breast pocket or waist belt. The ST2-SR is designed to withstand temperature, vibration, impact, dust and spray. It is water resistant, however, do not subject it to running water, and do not immerse it in water. When
used in accordance with user instructions, the respirator continues to provide full protection.