From the introduction:
In 1983, TSR published the module named Ravenloft with the module code I6. It was written by Tracy and Laura Hickman and illustrated by Clyde Caldwell. This 32-page booklet had two outer folders containing maps by David Sutherland III. It spawned a 1986 sequel, I10 Ravenloft II: The House on Gryphon Hill; together, they formed the basis of AD&D 2nd Edition's Ravenloft campaign setting. In 2004, for the 30th anniversary of the Dungeons & Dragons game, Dungeon magazine ranked this module the 2nd greatest adventure of all time. This conversion guide allows DMs to run the original module with 5th Edition rules and provides a reference sheet for encounters.
A 20+ hour adventure for 5th– 7th level characters
Note the original module is required for the use of this conversion product.