Much like gold-filled, silver-filled is sterling silver that is mechanically bonded to a base metal like brass or copper. This is a physical bonding, rather than an electroplating bond which is much weaker. In order for a product to be considered silver-filled, it must have at least 1/20 of its weight in silver. This equals out to 5% silver. So, when you read that a material is .925/20 or 925/20, this means the material meets the minimum standards for being silver-filled by containing 5% silver. Our line of silver-filled wire is 925/10, meaning ours contains 10% sterling silver or double the amount of many other silver-filled wires.