Fit true to size. I usually wear size 9.5 or 10 in shoes, ordered medium in the socks and they fit perfectly. Great padding, breathability. The heel tab is great for protecting against rubbing on the back of running shoes. I run 3 to 4 times a week with these socks and have never had a blister or any irritation.

I have used the socks in casual sneakers and are awesome for this use as well.
Easily my favorite running sock. Cannot recommend these socks enough!

I love these running socks. Comfortable and wear well. As others have said, it’s probably best to size up. I wear a size 11.5 running shoe but wear these in XL. The fit is perfect.

I've been a runner a long time and I have a couple pairs of these. I actually do not like running in them but I love to wear them with my Converse! The tab keeps them in place but they're just short enough that they're a little hidden and they are so soft.

Just stocked up again on these socks. They are the only socks I wear to hike, run, work out or lounge around. They are so soft and don't fall down on me. Get these, you wont regret it.

I tried these bad boys for the first time on a casual four mile run. My feet felt nice and snug the entire run. The heel tab is also a nice luxury to prevent unwanted rubbing. I plan on purchasing more of these.

Got as a gift and here is what he had to say:

"These socks are simply the best as far as comfort and performance. I have trained in these, raced in these and worn around the house. I have replaced most of my socks with these."

I have a standard 10.5 mens foot. The large runs just about perfect with a little extra wiggle room. If your feet fall in the 9.5 Mens range, I'd suggest going with the size medium

I got these last week, and they instantly became my favorite running sock They're so soft and comfy. I need to order several more immediately!

Love love love these socks. I have now purchased three pairs of these sock so I can wear them almost every day. They are soft, not to thin but not to thick, and they don't fall down during a workout. Purchase these, you won't regret it.

No blisters, well-made/long-lasting, great heel tab, good color choices. 3/3 runners in my family prefer Balega Hidden Comfort socks!

Own multiple pairs. Great socks

Very comfortable and great cushioning in the right spots

Very comfortable, just the right amount of padding. Love the heel tab, keeps the shoe from rubbing against the heel.

These are by far the best socks I have ever owned!