The PureFunds ISE Junior Silver ETF (ARCA:SILJ) is designed to expose investors to a variety of silver exploration and mining companies. These companies were chosen as they stand to benefit greatly from the discovery of a new deposit, higher production at their existing mines or through becoming a target of a takeover from a larger company. The ETF is the first to hold junior silver explorers and producers only. Here's a glance at some of the companies that PureFunds is keeping an eye on. Fortuna Silver Mines (TSX:FVI) Fortuna Silver Mines was founded in 2005, and produced 4.6 million ounces of silver and 21,242 ounces of gold in 2013. It aims to boost those production numbers to 6 million ounces of silver and 32,300 ounces of gold in 2014. The company has two underground silver mines in operation, along with further property holdings in Peru and Mexico. Its mines are the San Jose mine in Oaxaca, Mexico, which produces gold and silver, and the Caylloma mine in Arequipa, Peru, which puts out silver, lead and zinc. In late August, Fortuna released an updated mineral resource estimate for its San Jose mine, showing a 42-percent increase in silver ounces and a 29-percent increase in gold ounces compared to the previous resource estimate. The PureFunds ISE Junior Silver ETF holds 221,835 shares of Fortuna Silver Mines at a total market value of just under $1 million. MAG Silver (TSX:MAG) MAG Silver is focused on developing two projects in the Mexican Silver Belt. The company works on its main projects in a joint venture with Fresnillo (LSE:FRES), with interest split 44 percent to 56 percent, respectively. Those projects include the high-grade Valdecanas silver vein as well as the Desprendido and Juanicipio discoveries in Zacatecas.