Some packages have been about 0.030 inch width undersize which makes it very difficult to load. Last pack seemed to be resized bigger. Some packages have been sized with a dull cutter which fuses the tops shut and makes them almost impossible to open. At 200 to the box fusing is a BIG problem. Having 26 years as a manufacturing engineer in the converting industry I understand the problem when manufacturing loses focus on quality as needed / used by the customer. Middle weight seems to be well balanced for durability and not filling the notebook with excess plastic. I use these by the thousands.
I used to order a name-brand sheet protector direct from the California manufacturer - no more! I am so glad I discovered the Staples brand. Terrific quality - very versatile. I even use them in the kitchen to protect my printed recipes! These have never failed to please. I would be lost without this brand - quite economical without loss of quality!
I teach music and have many binders filled with music that are sorted alphabetically by song. It enables me to pull the pages out easily to write comments on the music to turn the pages without ripping them off the rings and to easily place them and remove them at will in other binders. There is no glare so it is easy to see the music and the clear plastic allows me to see through to the music easily.