I bought these over Christmas and can highly recommend them:
<commercial links not allowed>
They're comfortable, there's no need for tape, and they hold everything back nicely. I've even slept in them a few times, though that's generally something I avoid.
Just be aware they do compress quite strongly and reduce circulation, so they'll accelerate shrinkage. But I haven't used my penis for penetrative sex in ages, and don't ever plan to again. My penis is a clit already as far as I'm concerned.
When I have occasional sexual urges I'll give myself a prostate massage, and keeping these on while doing so each time has greatly reduced my erectile response and I remain soft during prostate stimulation. My erect size has dropped to about 5.25" from almost 8". Penis shrinkage seems to require less blood circulation to the penis in combination with HRT in order to take place.
Moderator edit: I have removed a link to a commercial site.