What is the difference in the numbers, 1 through 5?
The number indicates regulator compatability. Regulator openings are different sizes depending on the manufacturer.
The different numbers match different regulators, seacure's website has the chart.
The size of the orifice that fits to the 2nd stage regulator. SeaCure website offers a sizing chart to tell you which size fits your regulator.
The number refers to the variant of the Seacure the matches with the regulators listed under each number. You need to look up the Seacure website or look at the packaging to see which number (style) your particular regulator falls under and then order that number. There is no obvious rhyme or reason that you can "guess" at. (I think it is based on the size of the regulators oriface that physically attaches to the mouthpiece.)
The numbers 1-5 are the size of the mouthpiece.
There is a size chart on sea cures website that shows what numbers fit what regulators
The number indicates the types of regulators the mouthpiece fits. Check the seacure website for the size chart or goggle the name of the mouthpiece for the link to the site.
The sizes are to accommodate the mouthpiece opening on regulator 2nd stages from the different manufactures.
LeisurePro will not let me provide you a direct link, however Seacure has a sizing chart on their website that details which size fits which manufacture. Use a search engine and search the web for "seacure mouthpieces" and you'll find the manufacture's website.
The numbers indicate different sizes, depending on your regulator. Use this chart to determine which size you need.
You can find a size chart on the Secure1 website.