What are these cylinders used for and their worth?

[kelpdog]

I recently purchased some used SCUBA equipment off Facebook marketplace, and in this batch of gear was 2 steel cylinders. Their markings are as follows

TC-3AAM230 DOT-3AA3130 M8004 REE26.2

X540 3255621 04/06+

From what I’ve gathered online from used classified posts. These are
-made by worthington for XS Scuba
-3130 PSI (with +)
-40 CF of gas
-steel

My main questions are…does anyone use these type of cylinders anymore? I’ve never see anyone use them, maybe that’s why they were discontinued.
What are they used for? (Ponies, stage, small twinset?)
What are they worth?
Thanks for the help! I’ve attached a photo of them.

 

[Tracy]

looks like an hp71.
heavy little thing. My wife dives them. They are great for short divers as rebreather bailout tanks.

 

[SlugLife]

I'd second "bailout tanks" as a primary use. One could also use them as a pony-bottle / redundant air. Technical divers would likely have a variety of uses for them as well.

Worth? Hard to say, it depends on local markets, and perhaps their hydro-date.

 

[runsongas]

X5-40 Cylinder

Service Pressure..........3130+ PSI
Buoyancy Full...............-6.3 Pounds
Buoyancy Empty...........-3.3 Pounds
Weight Empty...............18.1 Pounds
Outside Diameter...........5.4 Inches
Length..............................18.75 Inches

I don't see too much potential due to the negative buoyancy unless if you were running a pair for ballast basically in cold water.

 

[UofMI_Divegeek]

As a last resort:
Remove the valve
Replace valve opening with an eye bolt
Cut off the bottom

Discarded steel cylinders make great bells. (g)

 

[lostsheep]

Don’t cut them up , I could use those. DM sent

 

[211ratsbud]

I could use them too!

 

[lostsheep]

X5-40 Cylinder

Service Pressure..........3130+ PSI
Buoyancy Full...............-6.3 Pounds
Buoyancy Empty...........-3.3 Pounds
Weight Empty...............18.1 Pounds
Outside Diameter...........5.4 Inches
Length..............................18.75 Inches

Where did you find these specs? Was it from the old post here on SB?

My Google-fu is weak this morning and I can’t find much at all about these cylinders.

 

[Whitrzac]

The spe

Where did you find these specs? Was it from the old post here on SB?

My Google-fu is weak this morning and I can’t find much at all about these cylinders.

spec sheet from faber has them on it.

 

[lostsheep]

The spe
spec sheet from faber has them on it.

OP says these are worthingtons, DRIS shows some HP40 fabers but they have different specs.

Do you have a link to the faber spec sheet you are referencing?