Replacement CO2 diffuser disc Tow sizes available : Dia. 2cm/ 0.79inch; Each Pack comes with 10 piece. Helps to plants receive proper amounts of CO2, improve the growth and health of your plants with sufficient CO2 supply. The CO2 diffuser disc must be screwed as tight as possible when installation. Notice: The CO2 diffuser may release big CO2 during its first 1-3 of usage. When ceramic disc becomes saturated with water, it will then release fine CO2 , this is normal and may take up to 3 Colour:white+blue Material:PVC+quartz Package Contents: 10 x CO2 diffuser disc Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.