1. Water injection design, safe and convenient to use
2. High density PVC material, no water leakage, safe and harmless
3. Knob plug, good sealing, no water leakage
4. Good insulation, lasting warmth
5. Material: high density PVC
6. Capacity: small size about 280ml, large size about 520ml
7. Size: small about 17 x 11cm, large about 14.5 x 21cm
8. Weight: small about 40g, large about 60g