The number of VIX products has exploded in recent years. The two ETF options track mid- and short-term VIX futures: ProShares VIX Short-Term Futures (NYSEArca: VIXY) and ProShares VIX Mid-Term Futures (NYSEArca: VIXM).

Before the ETFs hit the scene, however, there were a number of ETNs through which investors could get their exposure, including iPath S&P 500 VIX Short-Term Futures ETN (NYSEArca: VXX), iPath S&P 500 VIX Mid-Term Futures ETN (NYSEArca: VXZ), VelocityShares Daily Inverse VIX Short-Term ETN (NYSEArca:XIV), VelocityShares Daily Inverse VIX Medium-Term ETN(NYSEArca: ZIV) and UBS E-TRACS Daily Long-Short VIX ETN (XVIX).

Make sure you know and understand what a VIX investment is and if its right for you; visit our VIX category.

Max Chen contributed to this article.