These shoes suck. I loved them at first. Got them as my trad shoes. So, they were tight but still comfy enough to wear them a whole day without being in excruciating pain. When I bought them, I got told that they basically don't stretch (or just a little).
Little did I know. They stretched a whole lot. Even with socks, they are way too big, especially the toe box and there is no way to tie them any tighter either.
I am terribly disappointed, especially as these shoes have not seen to much use either before stretching out that much.

Those shoes are useless for me and I am selling them again.

I would not recommend these shoes.

I love these shoes. They are extremely comfortable and great for bouldering and climbing. I have only used them indoors, but they seem like they would work well outdoors, too. I think they stretched just a little bit, but they definitely still fit me. The elastic laces are kind of worthless because they end up being way too long but the regular laces work just fine. I'm planning on buying this same pair of shoes as my next pair.

These shoes are perfect for indoor and outdoor climbing, as well as bouldering. I've used them mostly on indoor walls and sandstone and they've functioned very well. They're comfy enough to be able to stand around in while belaying, though I do have narrow feet that squeeze into pretty much anything. Good construction, they don't rub wrong anywhere and are holding up well. I haven't tried the elastic laces because the regular ones work just fine.

Great climbing shoes! I typically do sport climbing and can stay in them all day without having any discomfort. They were great right out of the box. I have slightly narrow feet and I am a size 8.5 in street shoes so I bought an 8.5 in the Sirens and 2 years later I havent regretted it.

I have climbed in different shoes, La Sportiva Testarossa, Evolv Electra, Evolv Rockstar, and 5.10 Anasazi among them. They above are all good shoes, but ever since I tried 5.10 Sirens I cannot wear anything else. I am now on my 4th pair if Sirens.

The rubber is great, this is 5.10 we are talking about. The laces allow for perfect tight fit that stays tight, unlike the velcros that always seemed to loosen for me. And the shoes fit me perfectly right out of the box, with no hot spots, rubbing, or irritation.

I wear size 7 in street shoes, and use size 6 in Sirens. It is a tight fit, but not painful. I find that the shoes stretch about 1/2 size, both length and width-wise.

I've been out of climbing for a while. Back in the day I used to climb in Five Ten Dragons and Boreal Matrix's, both shoe sized aggressively tight. It was surreal to me to have a shoe that I could pull hard on 10d/11a in the gym and not have to slip them off as soon as I hit the ground. The upper is super soft and stretches nicely. The rubber grips, well like stealth rubber always does, solidly. I tried to go cheap at first and bough a pair of Evolv's before this but the rubber just wasn't up to what I have grown used to with Five Ten and I quickly snatched these up.

Now the bad:
-stink, these shoes do not breath at all, and your feet will SWEAT!! I use cedar blocks in them to help afterwards, but they are still not allowed inside my climbing bag (I use the water bottle pocket on the outside for them)
-although exceedingly comfortable, I wish I had sized just a hlaf size down, after 2 months of 3-4 day a week gym climbing the rubber around the crease between my tows and top of my foot is starting to pull away, I think due to the ammount of pressure put on the spot when i climb
-the laces are WAY to long, both the regular and elastic are SUPER long. I got around this by cutting the elastics and burning the ends together about 2 inches above where the are tight on my foot, this way i can get in and out easily, but am not worried about stepping on my laces.

Overall, I love these shoes, they have there foibles for sure, but the comfort combined with the sweet rubber really make them my fave all around shoe.

Well everyone says climbing shoes aren't comfortable, but I found the foot squeeze in these to be too much. I had taken advice from other reviews and ordered an 8 for my 7.5 feet, but still didn't think I could wear them long enough to climb. I ordered a pair of Mythos from Backcountry for my Colorado climbing trip and loved them for my 5.7 to 5.9 sport & trad climbs - they are great shoes!

Great shoes - I have a hard time finding a technical shoe that fits my narrow, low volume foot. These are fabulous. The heel fit is great without digging into my achilles tendon and the last is curved enough to provide for precision edging without mangling my foot. Not the most comfortable for slabby, featureless, face smearing and long trad routes, but great for small edges and steep sport routes. I've tried about 10 different pairs of shoes and these are the bomb. I wear a women's 9.5 to 10 in street shoes and bought these in a 9. Perfect.

Love them. Seems to be sized a little small. I normally wear a 7.5, got these in an 8. The fit it great. Snug heel, good arch, doesn't kill the toes. I can wear them on long multi pitch without discomfort and they still perform well as good as I could want them. Just got done with a week in Cochise Stronghold. Everything I did required trusting feet a lot!. It didn't take long to learn to trust the shoes to smear all over those walls.

These shoes are great. The rubber is def. superior to the other climbing shoes I have (Mad Rock something). I have been using them for a month indoors and outdoors- they hold well in both conditions. The only thing is that my feet cramp really easily and really quickly when I use these shoes on thin climbs outdoors. I wear size 8 for regular street shoes and my Sirens are size 7.5. Maybe I have wide feet and have to order size 8. Other than the cramping when one the rocks, they're pretty comfortable for climbing shoes.

These shoes fit like a glove all around- my indoor climbing has improved tremendously since I don't feel like they are even on. I do take them off when I'm standing around though

These are very comfortable climbing shoes. I recently used them bouldering outside and my feet were very happy all day. The sizing was a little inaccurate. They seem to run small.

These are my first pair of climbing shoes and I love them. They've made an awesome difference in how I climb! I was warned that climbing shoes were supposed to be awful to begin with for 20-25 indoor pitches but these are totally fine, obviously more snug than my regular shoes but after the first use (a 3hr session) only one of my big toes was a bit sore from being more squished than usual but no blisters or anything. I have a wide foot and these are such a good fit - if you're new to climbing these are totally worth the $$. They're a great beginner shoe!! Thanks 5.10

These climbing shoes are great. They are advanced without feeling like those totally hardcore shoes where your arch is pulled into this uncomfortable "C" shape. I've worn them climbing in the gym and outside, and the sole is nice and grippy.

these have an awesome fit right out of the box. They are great for bouldering and are very comfortable. It is nice they are all synthetic so you do not need to go through the painful break in time that the leathers need. Great gym climbing shoe. It does not much arch, but you can force it into an arch easily. The lace up system is ice, you can tighten select spots really easily. Great women's climbing shoes!

Great fit - true to to size... but the first time I used them at the climbing gym, both heels cracked down the middle! Unbelievable. The site took them right back and even sent me a shipping label so I wouldn't have to pay for shipping for the return.