They range from 34cm up to 46cm. The springs should be tensioned at 1-1½” so you need a spring that is smaller than the actual gap between the holes.
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Fashion Black Plastic Spring Elastic Keychain Fishing Coil Elastic Lanyard Spring Coil Lobster Clip Keychain Anti-Lost Hanging
Aliexpress UK
Keep your cat entertained for hours with these lightweight and bouncy spring toys! Perfect for indoor play, these bright coils stimulate your cat’s natural hunting instincts, encouraging exercise and reducing boredom.
eBay
1.2m/2m/3m Max Stretch Plastic Spring Elastic Rope Fishing Lanyards With Carabiner Boating Ropes Anti-lost Phone Keychain Lock
Aliexpress UK
Color: Multicolored. Put a little "spring" in your cat's step with these colorful, bouncy, plastic spring cat toys. Your cat will have fun chasing them around while their unpredictable bounce will drive them nuts!
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2pcs Rock Fishing Float LED Electronic Night Light Floats Freshwater Luminous Plastic Spring Fishing Bobbers For Crappie Catfish
Aliexpress UK
🚀Bouncy & Fun: Springs roll and bounce unpredictably, stimulating cats’ hunting instincts. 20pcs Cat Spring Toys Colorful Plastic Interactive Coil Toys for Indoor Cats. 🐾Lightweight & Easy to Play: Only 4g per spring – cats can carry, chase, and bat them easily.
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Winding Board Fishing Tackles Plastic Wire Wrap Spring Hooks Colorful Fishing Line Hooks Portable Line Clips Fishing Clamps
Aliexpress UK
Color: Multicolor (Random). - Funny cat spring toy, this is a perfect smart toy specially designed for cats to grow. QTY of Cat Spring Toy. - Material: Plastic.
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Stretch Lanyards Plastic Retractable Tether Spring Elastic Rope Coiled Anti-Lost Keychain Multi-functional Fishing Accessories
Aliexpress UK
Washing and cloth pegs. Strong Plastic Clothes Pegs. The pegs have a rust free spring. Made of strong plastic.
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Fishing Mesh Portable Fishing Net Plastic Tear-resistant Excellent Spring Shoal Fishing Netting Supplies
Aliexpress UK
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9KM 25Pcs Ewg Hooks Swimbait Hooks with Spring Pin with Twistlock for Bass Fishing - Soft Plastic Hooks
Aliexpress UK
Plastic Single Hole Spring Cord Locks Toggle Stoppers Sliding Cord Fastener Slider Lace lockers for Drawstring Rope Paracord End Tents Lanyard Craft. ✓ Available in a wide range of colours and patterns.
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Garden Expansion Spring Water Pipe, High-Pressure 8-Function Car Wash Spray, Durable Garden Plastic Water Pipe, 7.5M-30M
Aliexpress UK