I dont understand larger devices

My take it's that it's very relative. Some people will use large dildos, 2-3 fingers or whole hands, fists, penises... if you're a porn viewer you've probably seen it all. I guess it's mostly about practice and how big you want to go or how big is safe for you long term. 

While I do think that the Eupho and the tiny Peridise are the best toys in the whole line, the full feeling that you get with the Progasm brings different sensations, and with practice and relaxation you can use it without discomfort.

What I like about the smaller models is that I can start a session without any preparation, so my Progasm mostly stays in the box, but I don't have the feeling that the Progasm is "too big". To my eyes, it's just less convenient to use than the smaller models, and yes it can be a little harder to relax. 

With the Progasm your muscles have more to grab and its mobility can be surprisingly good once you're relaxed enough, and I *think* that you have better chances of going into auto-fuck than with other models, so some users will have the opposite opinion VS. what you present. 

@zentai

Such a good answer, I second every single point you made!

Yes I too agree with @zentai

You have to take into consideration anatomy, preference of toy size, response to toy, and desired effect. 

For me bigger toys don’t hinder sensations. Rather, speed and repetitive pounding does, as well as my clenching. So on a big toy if it is slow and I don’t over clench, it is just as subtle as a small toy. However I don’t own the programs. I do use my njoy wand and equivalent sized dildos that I hold in place like a hands free toy. I get contractions, and since the toy is held in place , the contractions cause my rectal walls to press gently up against it over and over. I’m not Saying this is a typical experience, but just explaining the appeal for me, because we are all different and because you asked.

For me in order to feel any kind of orgasmic response i need clear, defined muscle contraction. Bigger devices totally, utterly hinder this movement.

I have wasted money on larger devices and im pissed off.

That is the gamble of sex toys. You can’t return them. I too have made purchases I regretted (lelo Hugo, being the most expensive and most worthless of my sextoys, because it turns out vibrations are an impediment to me, and I bought it well before I knew about aneros devices). But the fact that these toys work for others means that they are not scams. Instead of being pissed off, why not just pop in a toy that works and smile!! And you can try them every year or so, maybe one day you will like them...