Japanese manufacturer Hanayama has been producing cast mechanical puzzles called "Cast", then "Huzzle" since 1983. "Huzzle" is a combination of two words:
はずす (hazusu - to detach) + パズル (pazuru - puzzle) = はずる (hazuru - huzzle)
Huzzle difficulty varies from 1 (easy) to 6 (difficult). Depending on the reedition, the difficulty score can sometimes vary. This is the last difficulty level that indicated.
Also sometimes name can change. In that case, both designation are given. Also small series were produced, sometimes in association with other brands.
Symbols meaning: Marine serie (6 huzzles of 1,2,3 level) Discontinued huzzles