Eric, if you go to siliconenozzles.com, look under 'Product Groups' on the right the group named 'Retention Nozzles / Plugs', about 2/3 of the way down and click on it, you will see a lot of plugs. Scroll down to the bottom line, and you'll see the blue plug in the middle named 'SPD3.0 - 3 Inch Diameter Super Retention Silicone Nozzle.' That's the plug I have. Click it and you'll see several options for ordering the plug. I ordered: color--green; softness--00-20 Extra Soft; bore size--5/16 inch; No Connector Pack. The cost was $45 plus shipping.
I use the plug for enemas, and I also use it just like an ordinary butt plug by plugging the bore hole through the plug with a plastic 'toilet bolt', (the kind used to attach a toilet seat to a toilet, which is available in a two-pack for a couple bucks at Ace Hardware, Walmart, Home Depot, Lowes, etc.). Get it without a bore hole if you only want to use it as a plug.
The shape of this plug looks like it might not come out once you get it in, but in the Extra Soft material this is not at all a problem for me. I can get it out fairly easily and completely painlessly whenever I want by pulling it out by its base. I've never had this plug try to pop out on me. It doesn't leak a bit while its in me, liquid or gas.
Inserting this plug in Extra Soft silicone is a little tricky, but now that I've got the hang of it, I can pop this plug into me in two seconds with zero pain. It's tricky because the soft material is so squishy and floppy. You can squeeze the widest part of the plug in your hand and compress its diameter down by 40%, which makes the plug grow an inch or two in length. Let go, and it pops back to normal. Pressing on the base alone does not do enough for me to get the plug inserted. The plug is too floppy. It won't even stand upright by itself on its base. The insertion technique I use is to put the bottom of the base in the palm of my hand, wrap my fingers over the base and extend my thumb-tip and fingertips as far as I can to apply pressure at five points around the bottom of main cone part of the plug. Then I push as hard as I can in one forceful motion, and the plug pops right through my anus. This is totally painless for me because the material is so soft. Once inserted, the plug expands so it feels like it's completely filling and conforming to the shape of my rectum. It feels like it can't expand back to full diameter inside me and it's pushing the walls of my rectum outward in all directions to try to get back to its full diameter. It puts constant pressure on my prostate--very stimulating. This is a unique feeling for me. I think inflatable plugs may feel like this, but I've never tried one.
If you normally are able to insert a 3-inch plug in a rigid material, you might not have the same experience I have had with this plug. I've never tried a 3-inch rigid plug because I can only insert a 2.5-inch plug in a rigid material with a slow, careful, back and forth insertion process over a minute or two. If you've never inserted a 2.5 inch plug in a rigid material, you might want to try the next size down, which is 'SPD2.5-Extra Large Retention Style Silicone Nozzle.' The same shape plug also comes in 2.0-inch, 1.5-inch, and 1.1-inch diameters.
I find the Extra Soft 3-inch plug so comfortable that I sleep with it in. A few weeks ago, after a total clean out with a 66-inch colon tube, I inserted the plug with the goal of keeping it in for as long as possible. I slept one night with it in, kept it in all the next day, slept another night with it in, and then kept it in until late evening of the second day. At that point I started feeling painful gas cramps on my left side. I had to to pull out the plug at that point to release the gas. So my record with the plug in is just over 48 hours, and my anus and rectum were completely comfortable (and stimulated) the whole time. That's a comfortable plug!