
Activity Play Mattress Set - Turquoise
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Transform Playtime with the Monboxy Convertible Play Sofa
Unleash endless possibilities for fun and creativity with the Monboxy Convertible Play Sofa. This innovative piece is more than just furniture; it's the ultimate gift for children, offering a blend of excitement and education. Perfect for children from 1 to 16 years, it serves as a sofa, play gym, sleepover mattress, tent, playhouse, and much more. Its versatility engages kids in imaginative play, keeping them active and away from screens.
Key Features & Benefits:
- Safety First: Rounded edges ensure your child can play freely without the risk of injuries.
- Encourages Development: Boosts motor skills, problem-solving, and independent play while fostering curiosity and spatial awareness.
- Ideal Montessori Toy: Supports open-ended and independent play, aligning with Montessori principles.
Included in the Set:
- Base Mattress: Thick foam mattress with removable, washable covers. Size: 170 x 85 x 15 cm.
- Flexible Mattress: Thin, bendable mattress for versatile play. Size: 170 x 85 x 8 cm.
- Trapezoidal Pillows: Two pillows with removable covers to inspire creative building. Size: 56 x 56 x 31 cm each.
High-Quality Materials:
- Fabric: Made from 100% polyester, certified by OEKO-TEX® STANDARD 100 for safety.
- Foam: Flexible polyether polyurethane foam, also OEKO-TEX® certified.
Simple Storage & Care:
Monboxy sofas effortlessly fold for minimal storage, with easy-to-clean, removable fabric covers ensuring hassle-free maintenance.
Shipping Information:
- To Estonia, Latvia, Germany, Sweden, Denmark, Poland, Slovakia, Hungary: 24.99€
- Lithuania, Spain, The Netherlands, Belgium, Ireland, UK, Luxembourg, Slovenia, Czech Republic, Austria, Italy, France: 29.99€
- Finland, Bulgaria, Croatia, Greece, Portugal, Romania: 49.99€
Bring home the Monboxy Convertible Play Sofa today and equip your child with a dynamic space that nurtures creativity and joy.
SHIPPING + RETURNS
THE RATHER IMPORTANT BITS
This rather lovely piece ships directly from our brand partner - we work with independent brands who are absolutely brilliant and work frightfully hard to create beautiful things.
SHIPPING DESTINATIONS
Now, here's the thing - our wonderful brand partners ship to lots of different places, but not all of them can ship worldwide.
Some are brilliant at international shipping, others prefer to keep things closer to home.
At checkout, you'll see exactly where this particular brand can send your goodies.
We're terribly sorry, but shipping costs do vary rather wildly depending on where you are in the world. The exact figures pop up at checkout - no nasty surprises!
RETURNS
You have 14 days to return items.
Now, we absolutely adore our brand partners - they work incredibly hard and we do try to support them as much as we possibly can. So I'm rather afraid we have to pass the return postage costs back to you. Frightfully sorry about that!
🌍 PLEASE CHOOSE THOUGHTFULLY:
Our wonderful partners put their hearts into everything they make.
Ordering multiple sizes to try at home is rather hard on our planet and makes things jolly difficult for these brilliant independent creators.
When in doubt, do ask us first!
The brands we work with all have a chat option, and they love to chat!
PAYMENT
We're frightfully modern and accept all the usual suspects:
Visa, Mastercard, American Express, PayPal, Apple Pay, Google Pay, and Shop Pay
SECURE AS HOUSES
Everything's properly encrypted and secure - your details are safer than the Crown Jewels!
All prices in lovely British pounds £ GBP, though international chaps will see converted prices.
Any payment pickle? We're here to help sort things out! Contact us

We are Sostter
We met as children. Grew up a few streets apart. Built dens, rode bikes, and eventually — built Sostter.
It started with a shared love of objects that meant something…things with a past, or at least a purpose.
Now, Sostter is our grown-up version of a treasure hunt: a space where design meets storytelling.
We curate independent brands, one-of-a-kind finds, and everyday essentials with character.
Giving Back
We’re proud to support Sutton Night Watch, a grassroots UK charity making a real difference in the lives of those facing homelessness. Through regular donations of stock, supplies, and essentials, we back their mission to offer warmth, dignity, and practical help to anyone in need — right where it matters most.
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