after much thought going into buying an ab wheel, i'm glad i went with this one.
from reading other reviews for other ab wheels, having 2 wheels was one criterion and another was making sure the wheel wasn't made of hard plastic and having ridges.
upon receiving the product, it comes with a mat for your knees and i would say to just throw it out, or find some other use for it as it's not very wide for it to be useful
the rolling aspect of this product is smooth. very smooth. i'm sure if yours isnt smooth, you should probably request a new one as i've rolled it on hardwood floors, carpet and yoga mats. so far for the past couple of months that i've had it, it doesn't seem like it'll lose the smoothness
as far as the handles go, i'm not sure what that other reviewer was talking about but for me, 1 star gets taken away because i dont find the girth to be large enough. if you have small hands i suppose it would suffice but for me, perhaps lifting heavy weights increased my hand size so i find this to be smaller than i prefer.
aside from that, for the price, i'd say it was a good buy
Black Mountain Products ab roller offers a dual wheel design for superior balance and functionality. Each roller is designed with a strong and sturdy base for gym and home use. Ab wheels are the perfect choice for toning abs, building muscle and burning fat. Using the Black Mountain Product double ab wheel allows you to strengthen your core, as well as your shoulders, arms and back. Each ab wheel is ready to use out of the box, with no assembly required.