As others mentioned, it's the same fund named "Total Stock Market Index" offered by Vanguard.
The options (or share classes) you can choose are:
Investor Shares, Symbol: VTSMX, Expense Ratio: .17%, Minimum Investment: $3k
Admiral Shares, Symbol: VTSAX, Expense Ratio: .05%, Minimum Investment: $10k
Institutional Shares, Symbol: VITSX, Expense Ratio: .04%, Minimum Investment: $5mil
Institutional Plus Shares, Symbol: VSMPX, Expense Ratio: .02%, Minimum Investment: $100mil
Exchange Traded Fund (ETF), Symbol: VTI, Expense Ratio: .05%, Minimum Investment: Cost per share, you can buy a single share