Check out FTM Prosthetics and Reelmagik packers. I have tried almost every kind I have come across, and these two are the best. They don't carry an stp, but it's easy to convert the packer into an stp model. Mango at
FTM-STP.com offers the best stp spoon type, but the packer is very cheap. I used the spoon off the Mango with some surgical tubing [can be bought at
4fishen.com], run a hole through the packer with a tent peg or ice pick, then feed your tubing through. If you have a hard time making the hole, get the tent peg hot and it will run through smoothly. It's worked great for me. Let me know if you have any questions.