For a long while there has been a combination of gas fittings available for cartridges intended for camping and trekking purposes. This is a result of being a well established product arena but also open to competition and new ideas which has led to some confusion. We'll try to explain...

The original early gas cartridges typically manufactured by Camping Gaz had no valve and relied instead on the adaptor of the (lamp, stove) appliance to actually pierce a hole in the top of the cartridge and simultaneously seal it with a rubber or silicon o-ring. These 'Bleuet' cartridges were therefore cheap and reliable and popular but as they have no 'extras' they could not be removed from the appliance until fully exhausted. With all canisters as the gas level drops so does its pressure so there can be a frustrating period of low gas pressure as a pieceable cartridge nears expiration but still isnt sufficiently empty to discard and replace. Also with this type, if you intend having more than one applicance, a gas lamp and gas stove for example, you will need a minimum of two canisters - one for each device. On the up side, this type is still very well supported around the globe and international travellers can usually pick them up for a tiny sum just about anywhere.

As an alternative to the pieceable type and to address its usability issues a resealable type of canister appeared on the market over 20 years ago. This relies on a thread which when mated with the stove or lantern causes an internal Lindal self-sealing valve to allow the gas to be released. This has massive potential advantages including only needing to carry one canister for multiple uses, the possibility to use on other (non camping) devices such as blowtorches etc and interoperability between brands. The chief downsides are that the canisters themselves are slightly more bulky and costly as a result of the inclusion of the valve but of course there's no wear and tear on the appliance's piercing component that occurs when initially fitting the piercable type of canister hence the costs probably balance out when you take into account the costs of parts or replacing your applicance. There is also an argument that says it is safer to remove the cartridge when not in use as there is no possibility of a fault on the appliance itself or the appliance being accidentally turned on to cause a dangerous build of gas in some unwanted location or indeed to run the cartridge empty when you least expect it. 

The potential for a myriad of screw fittings was headed off by ISO (International Standards Organisation) who drew up the EN417 thread (formerly known ad BS 5329:1988) connector standard by which most manufacturers now use and to which legally they MUST adhere if they state the appliance or canister is ISO/EN compatible. That said, there is usually strong advice from each manufacturer only to use the brand of cartridge that matches the same brand as the appliance. This is partly due to manufacturing tollerances and reduced risk of damage or risk of fire from badly made or poor quality alternatives but probbaly more likely to do with the legal complexities of assigning liability (blame) in the event of an accident or explosion. Either way, we would always support sticking with the brand you choose wherever possible as it reduces an element of risk when working with such a volatile substance as liquified inflamable gasses. If your main brand is not available, try at least to stick to well known brands such as Markill, Go System, Camping Gaz, Coleman,Primus, Taymar or similar rather than use unbranded or doubtful local brands.

Another type of resealable cartridge using the same Lindal self-sealing valve technology has been deployed by Camping Gaz - one of the most well established brands in this field. It uses an unthreaded push-fit style of attachment which appears similar to the ISO/EN fitting but without any thread, this is known as the CV fitting and is incompatible with the ISO screw fit types. The good news is that Markill, the legendary German manufacturer of quality stoves, market an adaptor for CV to ISO fittings which is excellent for world travellers and the CV is becoming dominant in some markets. 

Other fittings you may come across include the Gamping Gaz CP bayonet style or others developed specifically for limited ranges of products and which tie the customer (you) into the one brand. In our opinion, these non-standard fittings should be avoided if possible unless you have an overwhelming reason to purchase an applicance which relies on a specialist cartridge.

There are of course many much larger styles of canister/gas bottle and many styles of attachment typically reserved for multi-burner stoves, bbqs and patio heater appliances. These typically require an external regulator whose fitting and flow rate depends on the type of gas used (propane or butane or a mixture or both) but further details of which are beyond the scope of this article.