This intricate puzzle is different to any we've seen before and wonderfully challenging! Like Sudoku in a puzzle! As a difficulty benchmark, I (age 41!) can do the small one in 5-10 minutes but my 6-year-old is challenged by it. The medium one I reckon would take me an hour (but we have a few reports of 10-11 year olds managing it in 15 minutes!), and the large one takes adults quite a few days if not longer (except one lady did it in an hour, people are amazing!). What it containsA novel wooden puzzle with its own wooden storage cover. 0.5cm thick and: Small: 17cm wide, 20cm high. 7 pieces Medium: 25cm wide, 29cm high. 19 pieces Large: 32cm wide, 37cm high. 37 pieces  Feel great about where it comes from Raw materials from Europe? Poland - Yes Organic? TBC Manufactured in Europe? Yes - Poland What's it made from? Sustainability-certified* birch plywood, varnish recommended for toys, natural coconut oil. What's it packaged in? Nothing! Shipping packaging from manufacturer to us: Plant-based packing peanuts, cardboard box, recycled paper Plastic-free? Yes 100% Vegan? Yes Animal-cruelty-free? Yes Reused upcycled or recycled? No - new wood * We're not allowed mention which certificate because of bizarre bureaucracy, for details search our site for 'Not allowed to say FSC'. Feel great about where it goes after you've used it Biodegradable compostable?Yes 100% Reusable refillable? N/A Recyclable? Yes! Feel great about you and your child using it Great for ages: 3+ Shelf life: Indefinite Awards: 1st place: 'Child-Friendly World' competition 2019 (Poland's oldest toy competition); 1st place eco company in Baltów; Be the Change! competition; among others Safety standards met: relevant European standards for toys (CE-marked) Solvent-free? Yes Gluten-free? Yes Peanut-free? Yes Soy-free? Yes Lactose-free? Yes Easy to wash-off clothes / skin? N/A Improvements we're working on in this product: None, we think it's perfect! But let us know what you think! Search terms: logic puzzle, geometric sudoku, Stuka Puka