The CBOE VIX is a well-known index representing market expectations for volatility over the next 30 days.
The CBOE SKEW is an index reflecting the perceived tail risk over the next 30 days.
When the SKEW rises over a certain level (~140/150), that means investors are hedging their exposure with options, because they are worried about an incoming market crash or a...
Like a old faithful calculator the Tail Indicator - 84 will calculate the tail strength of the forces that drag the price against its momentum.
ps:.. the pun is totally intended. :)