Both are made by Upright, and have the same design. But which one is better for you?

Upright launched on the scene a few years back with a posture device worn on the back that buzzed your back straight when you started to slouch. The company has since evolved to include two devices: the Upright Go S and the Upright Go 2, both worn the same way and with an almost identical design.

Here is how they both fared during our recent testing.

Both devices are the same size, same design, and created to work the same way.Lauren Barack/GearBrain

Both the Upright Go 2 and the Upright Go S have an almost identical design, 48 mm in size, shaped the same and worn in the same spot — along the midpoint of the back and stuck with adhesive stickers to the skin or draped while attached to a necklace.

The two connect to the Upright app, and pick up on movement from someone as the device has worn. They deliver a vibration which can be adjusted in strength when the sensor detects that someone has started to slump forward or slouch.

Both Upright devices come with a travel case. But the Upright Go S comes with a soft case which can hold the sensor — and has an opening for the cable so it can be charged while in there. The Upright Go 2 comes with a hard case that works the same but protects the device a little better.

You also get alcohol wipes and hypoallergenic adhesives with both devices. But you get 10 with the Upright 2 and just 5 with Upright Go S.

The Go S, on the left, comes with a soft-sided case while the Go 2 has a hard case. You also get adhesive tabs so they can be attached, and worn, on your back.Lauren Barack/GearBrain

The Upright Go S is supposed to have 2.5 days of battery life, and the Upright Go 2 is said to have 5 days of battery life. But in our tests, we saw the Go S battery drop by 10 percent after one our of use. The Upright Go 2 had a longer battery life, and we were able to use it for multiple days without it needing s recharge.

With two sensors inside the Upright Go 2 as compared to the Upright Go S, I wasn't surprised to see that device more sensitive to my movements. That meant I got more alerts and quickly when I started slouching, or basically when my shoulders slumped forward. I found the Upright Go S less responsive, even after setting the range to one that was more strict.

They both performed similarly in terms of their vibration, and the strength. Both were audible when vibration was high. I did find though that the Upright Go S seemed to have a wider range, staying connected to the app at a distance that had previously disconnected the Upright Go 2.

Both cases allow you to loop charging cables through an indentation at the end, so you can boost the battery of the wearables while they're inside.Lauren Barack/GearBrain

The Upright Go 2 can be picked up for $99.95 while the Upright Go S is just $59.95. That's a $40 difference. If you want to wear it as a necklace you'll need to spring another $20 for one of those, or you can use the enclosed adhesive strips and then pay $10 for an additional 10. We are seeing the Upright site offering the Go 2 for a substantial break of $69.95 — which is a $30 price cut and almost in line with the Go S.

A $40 difference between the Upright Go S and the Upright Go 2 is fairly big considering they're both the same size, and don't really have different features between the two. Yes you get a soft case with the less expensive Go S compared to the hard case with the Go 2. And the battery life is longer with the Go 2. But mainly, what both are designed to deliver? That's the same.

I found the Go S to be less sensitive to my shoulders hunching or my back curving than the Go 2 and that may be related to the single sensor in the Go S, and two sensors in the Go 2. Yet, the Go S still responded, and I definitely felt I was getting notified throughout my sessions when I was not taking care to sit up straight.

Is the Go 2 then worth the extra $40? You do get a hard case — but the soft case that comes with the Go S is actually substantial too. And the five extra adhesive strips are just a $5 savings. We did find the Go 2 to be more responsive than Go S. Is that worth an extra $40? Maybe not.

If you can get the Upright Go 2 at the heavily reduced sale price of $69.95 it may be worth paying the $10 extra to get the dual-sensor device. But if it's a choice between spending $40 less or more, it might be fine going with the Upright Go S. You're still getting a device that will work to alert you when you begin to slouch at your desk and connect with the Upright necklace and you'll save enough for 40 additional adhesive stickers to keep you going for more than a month. We think that's probably a good deal.