The base is 1.5" in diameter which will fit the majority of the 3.75" ReAction Super7 line

These stands fit the following figure lines - 

Kenner Star Wars vintage (1977-1985)

Kenner Teenage Mutant Ninja Turtles Vintage (1988-1997)

Kenner The Real Ghostbusters (1986-1991)

Hasbro WWF vintage (1990-1994)