Wooden Logic Puzzles | Mind Bender Puzzles | Brain Teasers Siiren brings you its fun range of Logic puzzles and Mind bender puzzles. These wonderful mind bending logic stress balls are guaranteed to give you stress as well as relieve you of it, as you work out how the blinkers to get them back together again. Brilliant and annoying fun. Don't say we did not warn you! Instructions NOT included....Good luck!