1.ATTENTION : Before order, please measure your DOG PLACING AREA to make sure the size of LITTER BOX is suitable. EXTRA SMALL SIZE : 17×13 inches Only for Puppy less than 6 lbs like Yorkshire Terrier, Chihuahua. if NOT, PLEASE CHOOSE LARGER SIZE 2.4 LAYER SYSTEM : 1. Top Artificial grass; 2. Middle –Grid keeps the grass elevated clean from the pee pads; 3. Middle pee pads; 4. Bottom Tray 3.2 ARITIFICIAL GRASS PADS : It is convenient for you to wash a grass while the other is available for use. Designed with reinforced tufts and a strong rubber backing to withstand the tearing of pet. The bottom of artificial grass features much more small holes, liquids can go through the grass pad quicker and won't sit on the surface 4.DOG TRAINING POTTY : Most dogs like to pee on the grass. However, your dog may need some training. If your dog doesn't come near it, you can leave some urine on the lawn, which will help your dog to get used to it. TRAINING PADS : 2 training pad included, 35.4×23.6 inches, very absorbent,leakproof.