Treasury bond exchange traded funds have been some of the most popular investments over the past week as investors turn to safer assets to hedge against the current bout of volatility.

Specifically, the iShares 1-3 Year Treasury Bond ETF (NYSEArca: SHY) was the most popular ETF for the week ended Feb. 7, bringing in $3.6 billion in new assets, according to

Along with its safe-haven appeal, SHY may have also acted as a cash substitute as the fund shows a low duration of 1.82 years and a 0.22% 30-day SEC yield. The low duration helps the fund weather changes in interest rates. Specifically, with an average duration of 1.82 years, the value of SHY’s portfolio would decline about 1.8% given a 1% increase in interest rates. However, the relative conservative nature of this fund means that investors should not expect outsized returns as the ETF has only gained 0.2% year-to-date. [ETF Chart of the Day: Got Good Credit?]

On the other end of the spectrum, the iShares 20+ Year Treasury Bond ETF (NYSEArca: TLT) has gained 5.0% year-to-date and typically outperforms in volatile market conditions. TLT comes with a 16.38 year duration, which means a 1% rise in interest rates could translate to a 16.4% dip in the bond fund’s price, but offers a 3.51% 30-day SEC yield. [Treasury ETFs: A Contrarian Play for 2014]

In between, investors can also tailor their Treasury bond exposure with iShares 3-7 Year Treasury Bond ETF (NYSEArca: IEI), which has a 4.48 year duration and a 1.27% 30-day SEC yield, and the iShares 7-10 Year Treasury Bond ETF (NYSEArca: IEF), which has a 7.48 year duration and 2.40% 30-day SEC yield. IEF has gained 2.7% and IEI rose 1.2% year-to-date.