This ETF offers exposure to long term government bonds, focusing on Treasuries that mature in ten years or more. As such, interest rate exposure for this product will be towards the high end, potentially creating an attractive yield profile; VGIT offers exposure to mid-dated Treasuries while VGSH is an option for those looking to focus on the short end of the maturity curve. VGLT probably doesn't have much appeal as a core holding, since the overlap with broad-based funds such as BND will be significant. But this ETF can be a useful tool for tilting exposure towards Treasuries with a bias towards the longer end of the maturity spectrum, lengthening the effective duration of a portfolio and potentially boosting the yield without taking on much in the way of credit risk. Like most Vanguard ETFs, VGLT is among the cheapest options available; commission free trading in Vanguard accounts may increase the cost appeal to those keeping an eye on fees. Other options offering similar exposure include TLT and TLO; the effective durations and yields on these products may vary slightly.