I have no idea, I prefer to stick with regular harnesses such as spareparts, or others where the harness may come with a free toy to use, but the main item being marketed is the harness- Those generally tell you sizes.

For example this harness :
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Lists the max waist size as 60''. Most of the harnesses, rather than 'strapons' will list waist size where as the ones marketed as strapons a lot of the time just offer dildo sizes.

To find ones that come with a toy, 'Harness kit' is your best bet- they still provide lots of info on the harness but also come with a toy, and you can swap the toys out for other ones with flared bases as long as you read reviews to be sure that harness has that feature, but most of the nicer ones do, as well as anything that doesnt come with a toy attached, because obviously you have to put one on yourself, so you know you can use more than one toy with those.

According to the product page, it goes up to a 38" waist/hip.

We have detailed information including sizing about that product on our company blog: link

You should also check these blog posts out about our new Universal Harnesses from the Fetish Fantasy Elite collection that are a lot more versatile and can be used with most dongs in your collection.

Plus there is a TON of new dongs and dildo attachments for these harnesses. Beginner harness, Heavy Duty and Breathable (for max comfort).

Hope this helps.
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i also love the dildos with the holster for the bullet