Amazon uses an ASIN - Amazon Standard Identification Number - to classify products. Almost every product on Amazon has its own ASIN, a unique 10-digit code.
There are instances where the product you have listed is also listed and sold by other Amazon sellers. If those other Amazon sellers have assigned their own weight to the product ASIN, Amazon will average all sellers' weights for the product ASIN. As such, the weight imported for that product may differ to the weight you have entered.
NOTE: in some instances, the product weight will pull in as 0 (zero). This has to do with the way Amazon stores data for duplicate items. Unfortunately sellers are unable to affect when entering in their own items.
If the product weights from Amazon are incorrect, you can use ShippingEasy's PRODUCTS catalog to override with your own weights. The PRODUCTS catalog will match the SKUs in your orders to assign correct weights to the products. Learn more about the PRODUCTS catalog.
Alternately, you may override the weight on these products, individually, while shipping. Learn more.