The envelope will hold any shape. I was able to mail a teddy bear by squeezing it in the envelope. I also was able to mail 3 kimonos in the same envelope. When you seal the envelope it will hold.Love the size of it, and the price is so much cheeper the uline!Will definitely be purchasing again.The work well and are a good size for books or clothing. I have ordered these in the past and the quality remains the same.Aseptable para enviar sólo ropa⁃ I purchased the 10” x 13” mailers and they were true to size. ⁃ I sell items, mostly clothes, online, primarily on eBay. These mailers are excellent for mailing items such as Jeans, pants, t-shirts and shirts. ⁃ These mailers are ideal for packaging small and middle sized items for sale online. They provide a ‘waterproof/water resistant’ aspect to the package just in case it is delivered by a postman during the rain and left in a wet place. The merchandise stays dry and you, as a seller, avoids an unhappy customer who will most likely return damaged merchandise, a worst case scenario for an online seller. ⁃ The mailers are also very light and add virtually no weight to the final package. ⁃ The mailers/envelopes also present a ‘professional’ look, compared to using used/recycled mailers/envelopes. The buyer feels like great detail and attention was spent packaging the item. This may result in a much needed 5 star rating for the seller, yours truly! ⁃ They did fit a regular pair of jeans, size 36 waist by 34 inseam, via priority shipping. They also fit a pair of normal pants, size 34 waist by 30 inseam, via first class package shipping. ⁃ The self-seal closure works well and seals the item inside. ⁃ The material used to make the mailer is thin but sturdy; it will withstand the normal mailing of a package unless someone is very rough or careless down the line of sorting/transportation at the post office/courier service. If you have anything fragile, sharp-edged or expensive that you want to mail, you may want to use a bubble mailer/padded shipping envelope or a cardboard box instead. ⁃ I’ve had/‘heard’ no complaints from the online buyers who received items that I sent using these particular mailers. The mailers must be holding the items well until the package is opened by the buyer.I haven't had any issues, but they are rather thin to where I feel the need to double bag them. I feel like they could easily tear when going through the postal machines. Like I said though I haven't had that come up but does concern me.Excelente calidad material bien hecho y duradero