A pack of 4 insert replacement sticks for large-sized Sustee watering sticks - Replace core every 6-9 months for best results. Easy-to-replace core refills – Simply twist off the cap, remove the used core, insert the new refill, and replace the cap. The core turns blue when the plant has enough water and fades to white when it needs watering. Sustee collaborated with Tokyo University of Agriculture to improve the design and function of each stick. Materials: polycarbonate (main body), nonwoven fabric treated with preservatives (refill) Individual refill insert dimensions: 0.4 x 0.3 x 10.0 inches (large) - Made in Japan, Weight: 0.009700339528 Pounds, Manufacturer: Sustee