The Norguard d-ring extension makes it easier to reach your back d-ring. The NH-140 is version without shock absorber, the NSA01PW07 is version WITH shock absorber. IMPORTANT to ensure for the additional 18" extension in your fall distance clearance calculations. If you connect a 6ft lanyard to a d-ring extension, you now essentially have 7.5ft lanyard and may require up to 23ft of fall distance clearance. Also need to ensure that two shock absorbers and not combined together.