Horst Friesen with Engstrom RespiratorHorst Friesen with Engstrom RespiratorBird Respirator, 1966Sampling machines and procedures as used on H-7, October 1967Sampling machines and procedures as used on H-7, October 1967Sampling machines and procedures as used on H-7, October 1967MA-1 Respirator, 1968MA-1 Respirator, 1968Respirator apparatus, 1968Respirator apparatus, 1968Bennett alarm modification using phonojack, 1970Bennett alarm modification using phonojack, 1970Bird respirator modification, 1971Bird respirator modification, 1971Bird respirator modification, 1971
