MES

MES builds aluminium scuba cylinders, and this is the MES range at Oyster Diving. It runs from the small 2lt and 3lt bottles, through the 5.7lt (40cf) and 7lt, up to the 11.1lt (80cf), in natural, black and white finishes. Whether you need a pony, a stage or a main tank, the sizing is straightforward. Every cylinder on this page is MES-made, listed with the dimensions and fill pressure so you can match it to the kit you already own.

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The MES range at Oyster Diving

MES makes aluminium scuba cylinders, and this page holds the MES range Oyster Diving stocks. It spans small slung bottles up to the size most divers use as a main tank, in natural, black and white finishes. Every listing carries its volume, fill pressure and dimensions, which is what you actually need when you are matching a cylinder to bands, a valve or a wing you already dive.

Small bottles: 2lt and 3lt

The 2lt is listed at 102mm diameter, 400mm long and 2.6kg, and comes in black. The 3lt is 117mm, 440mm and 3.6kg in natural. These are the sizes divers buy as a pony or a small slung stage: short enough to clip off without fouling your trim, light enough that carrying a second cylinder to the water is not an event in itself.

Mid sizes: 5.7lt (40cf) and 7lt

The 5.7lt is the one you will see called a 40cf, listed at 133mm diameter, 645mm long and 7.0kg, stocked in natural and white. The 7lt is 152mm, 614mm and 8.6kg, also in natural and white. Both sit in the gap between a pony and a full recreational tank, which makes them the usual pick for a stage or deco bottle you intend to stay down with.

The 11.1lt (80cf)

The 11.1lt is the 80cf alloy cylinder, the tank you have almost certainly dived on holiday and on your training courses. Oyster lists it at 184mm diameter, 662mm long and 14.4kg, in natural and white. It is the default choice here for general recreational diving.

Aluminium cylinders in practice

Everything on this page is an alloy tank rather than steel, and the two do not behave the same way in the water. If you normally dive steel and you are adding an MES alloy cylinder, do a proper weight check on a shallow dive before you build a plan around it. This is the single most common thing divers get caught out by when they change cylinder.

Diameter matters more than people expect. Across this range it runs from 102mm on the 2lt to 184mm on the 11.1lt, and that spread decides whether your existing bands fit and how the cylinder sits against your back or on a clip.

Fill pressures, threads and fittings

Fill pressures across the MES range are quoted as 200 bar and 207 bar depending on the cylinder, so read the individual product page rather than assuming the whole range is one or the other. It is a small detail that decides whether your usual fill station and your existing gear line up with what turns up.

All the MES aluminium cylinders listed here specify an M25x2 valve thread. If you are carrying a valve over from another cylinder or sourcing one separately, confirm that thread first. A mismatch there is the usual reason a cylinder goes back, and it is entirely avoidable.

Choosing your MES cylinder

Work backwards from the dive rather than forwards from the spec. A redundant air source or a short slung bottle points at the 2lt or 3lt. A stage or deco cylinder you plan to breathe from for a meaningful part of the dive points at the 5.7lt (40cf) or the 7lt. A main cylinder for ordinary recreational diving points at the 11.1lt (80cf).

Colour is not only cosmetic once you are diving more than one cylinder. Natural, black and white are all stocked across this range, and having your stage visibly different from your back gas is a habit worth picking up early.

After you buy

A cylinder is a long-term purchase that needs periodic inspection and testing to stay in service, and valves need looking after between times. Oyster Diving runs a servicing side alongside the shop: see the Oyster Servicing collection for what we handle. If you are building out a technical setup around one or two stages, the Technical Diving collection is where the rest of that kit lives, and the wider Cylinders collection shows the MES range alongside everything else we stock.

Frequently asked questions

Which cylinder brands does Oyster Diving stock?

This page is the MES range, so every cylinder on it is made by MES — that is the only brand you will find here. If you want to see MES alongside the rest of what Oyster Diving carries, use the wider Cylinders collection, where the full stocked range sits together.

What sizes do MES aluminium cylinders come in?

Oyster Diving currently lists MES aluminium cylinders in 2lt, 3lt, 5.7lt (40cf), 7lt and 11.1lt (80cf). The 5.7lt and 11.1lt are the ones you will hear called 40cf and 80cf. The 2lt and 3lt are the small bottles most divers buy as a pony or a stage rather than as a main tank.

Are MES cylinders 200 bar or 207 bar?

Both figures appear across the MES range — the listings quote 200 bar and 207 bar depending on the cylinder, so check the individual product page for the one you are ordering. It is worth confirming before you buy, because your usual fill station and any valve or bands you already own need to suit the cylinder you end up with.

Which MES cylinder works as a pony or stage bottle?

The 2lt and 3lt MES cylinders are the natural choices for a pony or a small stage — short and light enough to clip off without pulling you out of trim. The 5.7lt (40cf) is the usual step up when you want a stage or deco bottle with more in it. If you are after a main cylinder rather than a slung one, look at the 7lt or the 11.1lt (80cf).

What valve thread do MES cylinders use?

The MES aluminium cylinders listed here specify an M25x2 valve thread. If you are moving a valve across from another cylinder, or buying a valve separately, check the thread matches before you order — a thread mismatch is the most common reason a cylinder purchase has to go back.

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