If you've got sliding doors or windows that are sticking, squeaking, or just not rolling smoothly anymore, these MroMax replacement pulleys are your solution! Made from sturdy stainless steel with a silver electroplating finish, these aren't those flimsy plastic wheels that wear out quickly. The U-groove double wheel design provides better stability and weight distribution than single wheels, so your doors glide smoothly without wobbling. Each pulley measures 83mm long by 15.8mm wide (that's about 3.27x0.62 inches) with a wheel thickness of 7mm - perfect for most standard sliding door and window systems. You get two pulleys in the package, which is typically what you need for one door or window. Installation is pretty straightforward if you're moderately handy - just remove the old worn-out pulleys and replace them with these shiny new ones. The difference in how smoothly your doors operate will be noticeable immediately - no more sticking, jerking, or having to put your whole body weight into opening a stubborn sliding door! They also work great for cabinets, furniture, and other sliding applications around the house. The stainless steel construction means they're rust-resistant and built to last, so you won't be doing this replacement again anytime soon. This is one of those simple DIY fixes that makes your home feel so much more functional and eliminates that daily annoyance of struggling with sticky doors. Seriously, for such a small part, these pulleys make a huge difference in your quality of life at home!