How deep is the Helix supposed to go?

The entire body is supposed tp enter the rectum, leaving only the p-tab/tailpiece intersection outside.

Simple answer -- With the p-tab centered laterally on your sweet spot, the Helix should naturally settle into contact with your prostate. Properly lubed, it will find its own 'correct location.

Several months ago rumel posted a more graphic answer (which I can't find with a simple search) -- a diagram in the thread had the sphincter on the straight portion of the stem, above the notch where the stem narrows. hth.

(Note : Underlined Text is a Hyper-Link)
Zelarius,

This question arises every few months as new users join and haven't read much of the Forum. Some users have tried to get their Helix fully into their rectums, this is unnecessary, ineffective and incorrect.This image from the Aneros HOME page more accurately depicts the correct positioning of your Helix model when inserted.
The tip of the Aneros (while inside the rectum) pushes against the prostate gland. The walls of the rectum are very flexible and elastic, they will easily stretch to accommodate the shape of the Aneros. You will notice that the narrow 'waist' of the Helix will naturally seat itself at the most constricted portion of the anal sphincter muscles. Trying to force it further in (down to the 'Tee') will be futile as it will just tend to pop back out as the 'P-tab' arm will act as a spring to pull it back to the proper position.

The tip of the Aneros (while inside the rectum) pushes against the prostate gland. The walls of the rectum are very flexible and elastic, they will easily stretch to accommodate the shape of the Aneros. You will notice that the narrow 'waist' of the Helix will naturally seat itself at the most constricted portion of the anal sphincter muscles. Trying to force it further in (down to the 'Tee') will be futile as it will just tend to pop back out as the 'P-tab' arm will act as a spring to pull it back to the proper position.

What the hell? In my case, when the p-tab contacts the perineum the rest of the Helix's body seems to naturally slip in all the way to the stem, the "tee". 😕

But obviously I can be wrong. I'll see whether Helix works for me in that position.

My own Helix base position is about where rumel describes it; however, there are probably individual variables at work.

-- tissue elasticty along my rectal walls - probably not as 'stretchy' as in a younger guy and probably not as responsive to smooth muscle contractions
-- prostate size - mine is estimated at 45grams - not extreme but larger than the average bear. So, I probably get more positive 'contact' with less helix penetration. 😀

Although I'm 6 feet tall, I get a nice ride from an SGX and can suck it up into my prostate. 😉