Engineered for improved breathing ease, this evolution of 3M’s most popular maintenance-free reusable half mask is convenient to use, reassuringly reliable and now offers measurable improvements in comfort.
Over 30% reduction in exhalation breathing resistance*.
Studies show how important comfort and convenience are in helping ensure workforces comply with regulations and maintain performance levels whilst wearing respirators. 3M recognise this and have applied their proven skills in respiratory protection to significantly improve the wearing experience for our reusable respirator users.** Introducing the 3M™ Maintenance-Free Reusable Half Mask, 4000+ Series incorporating a newly engineered valve assembly that helps reduce exhalation-breathing resistance by over 30%.
Breathing comfort
Like its predecessor, the new mask is lightweight, well balanced and has optimal field of vision. Convenient to use and comfortable to wear, there are 4 versions in the range, each offering effective protection against differing hazards in the workplace.
Wearer Comfort
- Soft and flexible face seal
- Lightweight and well-balanced mask
- Low-profile and ergonomic design
- Easily adjustable straps for secure, comfortable fit
Convenient to use
- Ready-to-use, “maintenance-free” construction with integrated filters
- Designed to be compatible with most eyewear and hearing protection models from 3M
- Resealable bag provides convenient and clean storage between uses
- 4 versions available, each offering effective protection against differing hazards in the workplace
- Proven to consistently exceed minimum standards for filter service life

Product range and intended use
The 3M™ Maintenance-Free Reusable Half Mask 4000+ Series come in a variety of different product options:
3M™ 4251+ (FFA1P2 R D) provides protection against organic vapours (good warning properties and b.pt. > 65°C), up to 10x Workplace Exposure Limit (WEL) or 1000 parts per million (ppm), whichever is lower, and 10x WEL for particulates.
3M™ 4255+ (FFA2P3 R D) provides protection against organic vapours (good warning properties and b.pt. > 65°C), up to 10x WEL or 5000 ppm, whichever is lower and 20 x WEL for particulates.
3M™ 4277+ (FFABE1P3 R D) provides protection against organic vapours (good warning properties and b.pt. > 65°C), inorganic and acid gases up to 10x WEL or 1000 ppm, whichever is lower and 20x WEL for particulates.
3M™ 4279+ (FFABEK1P3 R D) provides protection against organic vapours (good warning properties and b.pt. > 65°C), inorganic and acid gases and ammonia, up to 10x WEL or 1000 ppm, whichever is lower and 20x WEL for particulates.
Standards and approval
The 3M™ Maintenance-Free Reusable Half Mask 4000+ Series meets the performance requirements of the European Standard EN 405:2001+A1:2009 for valved filtering half-mask respirators for gases, vapours and particulate combinations.
The importance of fit.
Respiratory protection is only effective if it is correctly selected, fitted and worn throughout the time that the wearer is exposed to respiratory contaminants. It is recommended that a face fit check is performed before entering the workplace. Fitting instructions must be followed each time the respirator is worn.
Step 1: Assemble/adjust head cradle by feeding the perforated strip through the buckle and pressing down on the stud at the required length. Repeat for second strip. Place the respirator over the face, fitting it comfortably on bridge of the nose, then pull the head harness over the crown of the head.
Step 2: If necessary remove the respirator and readjust the head cradle to a comfortable fit and repeat step 1.
Step 3: Take a bottom strap in each hand, place them at the back of the neck and hook the straps together.
Step 4: Tighten the top strap first by pulling on the ends to achieve a comfortable and secure fit.
Step 5: Tighten bottom straps in a similar manner. Strap tension may be decreased by pushing out on back side of buckles.
Step 6: Perform a positive and/or negative pressure fit check each time the respirator is donned.
Positive pressure face fit check:
1. Place the palm of the hand over the exhalation valve cover and exhale gently.
2. If the respirator bulges slightly and no air leakage between the face and the respirator is detected, a proper fit has been achieved. If air leakage is detected, reposition the respirator on the face and/or readjust the tension of the straps to eliminate the leakage. Repeat the above face fit check.
If you cannot achieve a proper fit, do not enter the contaminated area and see your supervisor.
Warning. Beards and other facial hair in the sealing area of the mask can cause leaks and reduce the protection for the wearer. Always ensure the mask forms a tight seal prior to entering a hazardous atmosphere. This can be controlled by performing a negative and/or positive face fit check. Do not use with beards or other facial hair that prevent direct contact between face and edge of the respirator.
* Exhalation breathing resistance of 3M™ 4000+ reduced by >30% for 120 lpm peak exhalation flow and >35 % for 160 lpm compared to 3M™ 4000 Series. Results measured by 3M in 2017 under laboratory conditions. Breathing rates shown as an example only.
** Johnson Journal of Biological Engineering (2016) 10:4 DOI 10.1186/s13036-016-0025-4 Factors influencing the implementation of RPE programmes in the workplace – UK HSE Research Report 798.