• Berkey blocking plugs for blocking unused filter holes in the upper chamber on all Berkey systems
• Large Blocking plugs is the plastic screw type 
• Small Blocking Plug are the white rubber plugs.  
• Both Plug types fits all systems 
• All Berkey systems come standard with the proper amount and size of blocking plugs.  In case of loss or damage, replacement plugs may be purchased individually. 
• Plugs are made of 100% safe BPA free non toxic material.
• 1 quantity will come with 1 blocking Plug