- 
        Signature
      
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        /s/ Diane L. Thompson, as Attorney-in-Fact
      
      
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        Stock symbol
      
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        ZVO
      
      
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        Transactions as of
      
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        May 31, 2021
      
      
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        Transactions value $
      
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        -$25,284
      
      
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        Form type
      
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        4
      
      
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        Date filed
      
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        6/2/2021, 09:23 PM
      
 
     
   
 
  
    Transactions Table
  
  
    
      
        
          | Type | Sym | Class | Transaction | Value $ | Shares | Change % | * Price $ | Shares After | Date | Ownership | Footnotes | 
      
      
          
            | transaction | ZVO | Common Stock | Options Exercise | $0 | +42.8K | +118.4% | $0.00 | 78.9K | May 31, 2021 | Direct | F1 | 
          
            | transaction | ZVO | Common Stock | Tax liability | -$25.3K | -10.8K | -13.64% | $2.35* | 68.1K | May 31, 2021 | Direct |  | 
      
    
   
  
    Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)
  
  
    
      
        
          | Type | Sym | Class | Transaction | Value $ | Shares | Change % | * Price $ | Shares After | Date | Underlying Class | Amount | Exercise Price | Ownership | Footnotes | 
      
      
          
            | transaction | ZVO | Restricted Stock Unit | Options Exercise | $0 | -42.8K | -33.33% | $0.00 | 85.6K | May 31, 2021 | Common Stock | 42.8K |  | Direct | F2, F3 | 
          
            | transaction | ZVO | Restricted Stock Unit | Award | $0 | +111K |  | $0.00 | 111K | May 31, 2021 | Common Stock | 111K |  | Direct | F2, F4 | 
      
    
   
  
    * An asterisk sign (*) next to the price indicates that the price is likely invalid.
  
  
    Explanation of Responses:
  
  
  
    Remarks:
  
  EVP, Operations, Office of the CEO