I got these to replace my Bodylastics (BL) which I purchased from Amazon in 2010.  The Black Mountain set is 1/3 the price of my BL set, but the hardware is not as robust.  In addition, these bands are rated a lot higher in resistance weight than the BL.  In the BL set, I used the 8 lb band for arm exercises.  With this set I use the 25-30 lb band.  Feels the same.  So if you really want a resistant band for some more strenuous exercise, these are probably not for you.  You can double up on bands if you like, but that's not the point.  The BL had two attachments which allowed you to secure the band to a closed door and pull against it.  Very good for traveling.  This one requires hardware that needs to be mounted if you are going to use them in such a fashion.  The 25-30 lb band I use provides for smooth, not jerky motion.  I like that.  This has a lifetime warranty.  We'll see.