Dusk2 here. Long time fan 1st time posting. Here goes.
I wear spinfit cp100 medium for everything. Don't like foams generally speaking.
Dusk stock tips are the best like the previous person said.
However, I'm in between sizes, stock small too small, mediums a tad too snug I get sore in long sessions. Off to look for tips that fit the 6.5mm nozzle.
Symbio W - hybrid foam with silicon outside. Wow these are super hard dense foams! You can't even compress them. If they fit they fit but these where way too firm and worse than stock. Didn't care for these or try to down size.
Kz starlines...I hope they'd stretch to fit the nozzle but nope! They're not advertising large nozzle fit but I was curious.
Azla-lights - ordered MS.. No better than stock and pricey. Some one suggested I trim the nozzle tube a bit.. I saw no difference or change. Want to try exelastic but they don't last and super pricey. Went looking elsewhere.
Spinfit cp 155 - medium. Out of the box perfect fit. They are more cone shaped and longer overall than stock dusk2 tips. (they tickle so it took time to get used to the sensation... Deal breaker for some). They are a very thin flexible silicon that as a slight negative trade off have less passive noise isolation. If at arms length I snap my finger I hear it loud and clear. Stock tips mute the sound wayy more. These became my daily favorites.
All the tip rolling shredded the dusk2 mesh filters. Stock tips and spinfit 155 where the only aftermarket tips I could mount and not shred the mesh.
Wildcard find - I happen to be listening to my Venture Electronics Bonus IE iem one day and the stock tip (only comes with 1) looked promising. It's soft and pliable and stretchy. Lo and behold it fit the dusk2! It gives me the comfort of the spinfit 155 but more noise isolation closer to the dusk stock tips. Best of both worlds! The only drawback is they are so squishy when I take the dusk2 +bie tips out sometimes the tip will stay in my ear. Also the $25 ve BIE only comes with a single ear tip so if you don't fit you can't get it in other sizes.
Tldr blessing stock tips are your best option. If you are in between sizes spinfit 155. If that don't work get a different iem.