Understanding the differences in gas cylinders and mechanisms between Equa 1 and Equa 2 chairs can help you determine which model you own. Once you’ve identified your chair, you can purchase the appropriate replacement cylinder below:

• Equa 1 Cylinder
• Equa 2 Cylinder

Checking the Gas Cylinder:

If the cylinder has already been removed, examine the top section:

• Equa 1: Features a small, protruding metal button.
• Equa 2: Has a flush button.

Refer to the graphic below for a visual comparison.

Identifying by the Mechanism:

If the cylinder is still attached, the chair’s mechanism provides another way to distinguish between models:

• Equa 1: Has a visible slot at the front where the key holds the cylinder in place.
• Equa 2: Does not have this slot.

Refer to the graphic below for a visual comparison.

Another looser way to estimate - year of production:

Because Equa 2 replaced the original Equa in Herman Miller’s lineup:

• Chairs manufactured before ~1995 are generally Equa I (the original version). 
• **Chairs made from 1995 onward are typically Equa 2. 

There isn’t an official “Equa I ends here, Equa II starts here” date published by Herman Miller (e.g., no definitive “last production year” for Equa I), but 1995 is the practical dividing line because that’s when the newer model was launched. 

Discontinued Version:

Does your cylinder have a screw or spring appearance? If so, that is a super-old version, and we don't have replacements for this style.

Here is a photo example of this discontinued version:

Identified your chair? You can purchase the appropriate replacement cylinder below:

• Equa 1 Cylinder
• Equa 2 Cylinder

 Still need help? Contact us!