StayflatsPlus Mailers | Rigid Shipping Envelopes | Tamper Evident Security with Peel & Seal Pressure Sensitive Closure | Built-in Corner Protection| White | 25 Per Case | 9-3/4" x 12-1/4"

I ordered these (in kraft) because in the product questions, the manufacturer stated they were made of 28pt cardboard. I bought these to replace my other 28pt mailers in the same size (9.75x12.25) from a different manufacturer because of inconsistent products with my other manufacturer, and when these arrived, I could immediately tell they were nowhere near as stiff. I weighed these and they were only 2.7oz vs 3.5oz for my normal 28pt mailers, which is a huge difference. Judging from the product weights in the listing, the white mailers in the same size, which are considerably more expensive, are actually 28pt, but the kraft ones are considerably lighter and are not.My old mailers were very reliable and would only need one piece of cardboard stiffener when mailing prints, but these would definitely need two. The corners in my old mailer were also practically indestructible, and these corners are very flimsy.However, I do give props to Stayflats for sending all their mailers in boxes that can handle the weight and don't break apart in transport (which has happened to me every single time with every other manufacturer), and their mailers come with no funny smell (also happens a lot with other sellers). The middle seam design is also something I prefer in my flat mailers that not every seller provides consistently.If these were actually more heavy duty 28pt mailers, they would easily be a 5 star product. But I don't know if I can use these for my business without worrying about my products being damaged in the mail. I'm honestly very disappointed because I thought I had finally found the one in terms of flat mailers.

Honestly these work great for sending art prints. I got the 100 pack of 6x8 I believe. It's a small brown envelope, very sturdy and all the packages I've sent have arrived in tact. I don't need to add any other packaging around it and if I put 1-3 prints inside it only costs me 2 stamps to send it (for anyone who is wondering). I am happy with this product and would purchase again!

I'm shipping artwotks and I ran out of my old white mailers. I tried this brown one and it's good enough. The adhession is great! As you can see in the picture, I tested how far my mailers will bend with the same weight placed on top of each. The brown one is dense so it's bends noticeably; lightweight so you can save slightly on the postage. I don't think it will crash in transit. I'll update this review whenever something happens. (I hope not). Unlike other mailers, this one has some perforation on the upper edge to fold the flap. It's odd to discover it at first but not a big deal.

I ordered the 20x27” size to ship 18x24 matted photos as Christmas gifts. I didn’t want to have to buy/cut cardboard to “sandwich” the matted photos and was hoping these would be stiff enough to avoid that. These are not stiff at all and I will absolutely have to use cardboard. If you’re looking for large envelopes for photos these are NOT what you want. Too heavy to ship back but severely disappointed nonetheless.

These are far more rigid than what I perceived from the other reviewers photos. I purchased the 17”x21” size to ship “12x16” art prints. They are more sturdy than I thought but I will still sandwich the prints in cardboard to be extra safe. I found that two 14”x18” cardboard sheets fit perfectly with a little room to spare. I cut the 14x18 sheets out with a utility knife and a metal ruler. If you are serious about shipping prints, you should do everything possible to ship them the best that you can. It might survive with no added protection but why risk it?I was thinking the extras that I have left could always be cut to a smaller size and the edges taped. I don’t see anything particularly special about the corners from the inside. Although the outer edges seem more rigid than the rest of the mailer. But this wouldn’t really matter with the added cardboard.

I bought these last year but started using them more frequently recently to ship stickers and small prints, and I gotta say, these are great! Just to be extra safe, I still put a layer of cardboard. However, you can totally get away with no extra padding. These are surprisingly lightweight too: just stickers and envelope is 1oz, and with the cardboard, they come out to 2oz! I will say: be sure to spend an extra few seconds rubbing your shipping labels onto these. While I've never had any issues with labels coming off, I could see it possibly being an issue depending on how tacky the adhesive is.

I use the stayflats as photo mailers and to mail desk calendars. The mailers are sturdy, seal well when you close them, and look professional, and I've never had a mailed item damaged in transit. However, when the package of 50 mailers arrived the packaging they came in resulted in some damage to one of the mailers where tape had been, so I won't be sending that one to a client.

They seal well but aren’t rigid. Were not great for mailing posters. Resulted in several damaged products and less peace of mind than other products

Way too thick and heavy for what I need. The pitfalls of buying on Amazon. You cannot see and feel the item before buying.