They are likely at least a little firm, but I would not purchase them. Jelly is not a body-safe material, particularly for anal play. They may leach phthalates into your body, which are know endocrine disruptors and possible carcinogens. They cannot be sterilized and will harbor bacteria. Plus, this model does not have a flared base or handle to keep the toy outside of your body, making it completely unsafe. If your butt can handle the size of the beads, what makes you think it might not suck in the last couple? Then you're stuck going to the hospital.
In this case I can't think of a single positive attribute aside from the beads being cheap, but it isn't worth the potential risks. I would recommend saving just a little bit more and purchasing a higher quality pure silicone plug or beads. Tantus and Fun Factory are great brands to look at. If you would like more specific recommendations, let me know and I'd be happy to search out some decent products for you!