Excellent value to buy in this quantity, and you know you will use them all within a few years if you use your blender a lot. I do not know if these are OEM or aftermarket, but they fit well and do the job so at a bit over 50 cents each with free shipping, this is an excellent value.Just remember to store them in a bag so they don't dry out, and don't forget where you put them! I have spare screw caps too since I have cracked a couple of those by overtightening. I was lucky and found an old blender at a yard sale recently that had the aluminum cap. The specifications have not changed over the years as they moved from metal to plastic so I bought the used blender for $5 just to get the nice glass container and metal cap!