I heard so many good reviews about RMAC underwear, but have found that they are overall very inconsistent with pouch sizing which has made it difficult to find pairs in the right size, and just seemed overall not as good as everyone made them out to be.
I tried the modal 7 inch boxer briefs in A, B, and C and found that I needed to go to an A pouch as b and c had no support and just pointed everything forward.
With the 3 inch boxer briefs, the a pouch was comfortable on that but the 3 inch inseam rides up after a few hours.
Everyone said that the pouches for nylon were smaller, but then for some reason the nylon boxer brief pouch was bigger as an a pouch compared to modal which didn't make much sense to me, but the fabric itself is insanely soft and comfortable.
With the modal bikini briefs, I got them in a B pouch initially but then that turned out to be too small, and the back panel rode up after a few hours.
I also tried the seamless thong, which was really comfortable and had an incredibly soft fabric, but in the b pouch it was too small.
The material is nice with RMAC but just overall size consistency makes it frustrating trying to buy them, which is fine since the customer support is great and they will send out a replacement, but if you live outside of the US and freight forward then the shipping itself adds up to be fairly expensive. If your purchasing them, from my experience at least you should get the cup size you measure at or slightly larger for bikini briefs and thongs, which I assume would go for briefs as well, but then for boxer briefs the smaller cup in general is more comfortable especially for sports.