The Invesco RAFI US 1500 Small-Mid ETF (PRFZ) was launched on 09/20/2006, and is a smart beta exchange traded fund designed to offer broad exposure to the Style Box - Small Cap Blend category of the market.What Are Smart Beta ETFs?Products that are based on market cap weighted indexes, which are strategies designed to reflect a specific market segment or the market as a whole, have traditionally dominated the ETF industry.Market cap weighted indexes work great for investors who believe in market efficiency. ...