Permitdrab, here's my experience with Silicone Nozzles colon tubes. I have a 66-inch CT-75 in 12 Semi-Soft, (my favorite by far), a 60-inch CT-122 in 00-20 Extra-Soft, and a 60-inch CT-152 also in 00-20 Extra-Soft. The CT-75 is the only one I know I am fully inserting past the splenic flexure, and I'm virtually certain it's hitting my cecum, or at a minimum going very deep into my ascending colon. I know it hits my mid transverse colon at about 40 inches, because I can feel it with my hand. Inserting it beyond my mid transverse is easy with very little resistance. The final 20 inches goes in and pulls out very smoothly, so I think it must be navigating my heptic flexure without any problem. I'm having an intense, perverse love affair with my CT-75, the best sex toy I've every owned.
I have inserted my CT-122 'all in' several times, but it's too soft to know for sure if it made it through my splenic flexure or not. It's so squishy and soft that it could be doubling back at my splenic flexure and I wouldn't know. I can't feel it with my hand over my mid transverse like I can feel my CT-75. That could either be due to the CT-122 never making it that far, or it could be the extreme softness of the 00-20 Extra Soft material. Insertion is more difficult and less pleasurable than my CT-75.
I wish I'd ordered my CT-122 in 00-50 Plus-Soft or 10-Soft. I ordered this tube with a 5/16 bore, so I might try inserting some stiff 1/4" ID tube into the bore to stiffen up the entire colon tube, and I may try putting some of Silicon Nozzle's Keeper Rings on the tip and along the tube so I can feel it enough to know what it's doing. These mods might make my CT-122 as much fun to use as my CT-75.
I can't insert much more than 30 inches of my CT-152, and it may be dangerous. After inserting about 33 inches or two occasions, I've had to use an alarming amount of force to pull it out. (No pain or blood, but very scary.) It is probably starting to double back at my splenic flexure and getting tightly wedged into the flexure or top of my descending colon. I think I'll cut it into two. I'll make a 30-inch tube and maybe 20-inch nozzle with a hand-carved tip.
You can cleanly cut this 00-20 Extra Soft material easily with ordinary scissors. The sensations of inserting 30 inches of a 2-inch diameter tube in 00-20 Extra Soft are so exciting that I'm certainly not going to throw my CT-152 away. If I order another colon tube from Silicone Nozzles, (not soon because I just had $4000 of dental work done), it will probably be a 60-inch, CT-103 or CT-122 in 10-Soft.
Please let me know in this discussion thread which diameters and softness grades you've tried and what results you've experienced. 12-Semi-Soft might work well in CT-86 or larger for me--don't know. Everybody is different, so we might not get the same results from the same tubes, but it's still good to know.