Its ok for an addition to an onahole but it is not something meant to be used by itself. You need a onahole as they are sold separate from the insert air pillow dx body .It is bigger than the standard version with two different slots to use depending on your onahole's size.
I'm 172 cm tall and I find this pillow too large, it's up in the face when trying to use. :P The smallest hole can fit a "Real Erotic Play" or "Virgin Age Admission".
For anyone 175 cm tall and shorter, I recommend the standard version: https://www.otonajp.com/insert-air-pillow
Remember to have an air pump: https://www.otonajp.com/foot-air-pump