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Alpha Pro Tech Ltd – ‘10-Q’ for 9/30/19 – ‘EX-101.DEF’

On:  Wednesday, 11/6/19, at 11:52am ET   ·   For:  9/30/19   ·   Accession #:  1437749-19-21693   ·   File #:  1-15725

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  As Of               Filer                 Filing    For·On·As Docs:Size             Issuer                      Filing Agent

11/06/19  Alpha Pro Tech Ltd                10-Q        9/30/19   59:3.2M                                   RDG Filings/FA

Quarterly Report   —   Form 10-Q   —   Sect. 13 / 15(d) – SEA’34
Filing Table of Contents

Document/Exhibit                   Description                      Pages   Size 

 1: 10-Q        Quarterly Report                                    HTML    420K 
 2: EX-31.1     Certification -- §302 - SOA'02                      HTML     27K 
 3: EX-31.2     Certification -- §302 - SOA'02                      HTML     26K 
 4: EX-32.1     Certification -- §906 - SOA'02                      HTML     21K 
 5: EX-32.2     Certification -- §906 - SOA'02                      HTML     21K 
54: R1          Document And Entity Information                     HTML     49K 
25: R2          Condensed Consolidated Balance Sheets (Current      HTML    103K 
                Period Unaudited)                                                
20: R3          Condensed Consolidated Balance Sheets (Current      HTML     28K 
                Period Unaudited) (Parentheticals)                               
33: R4          Condensed Consolidated Statements of Income         HTML     78K 
                (Unaudited)                                                      
53: R5          Condensed Consolidated Statements of Shareholders'  HTML     82K 
                Equity (Unaudited)                                               
24: R6          Condensed Consolidated Statements of Cash Flows     HTML     84K 
                (Unaudited)                                                      
19: R7          Supplemental Disclosure of Non-cash Financing       HTML     23K 
                Activities                                                       
34: R8          Note 1 - The Company                                HTML     25K 
52: R9          Note 2 - Basis of Presentation and Revenue          HTML     30K 
                Recognition Policy                                               
30: R10         Note 3 - Stock-based Compensation                   HTML     42K 
15: R11         Note 4 - Investments                                HTML     28K 
41: R12         Note 5 - Recent Accounting Pronouncements           HTML     32K 
47: R13         Note 6 - Inventories                                HTML     32K 
31: R14         Note 7 - Equity Investment in Unconsolidated        HTML     34K 
                Affiliate                                                        
16: R15         Note 8 - Accrued Liabilities                        HTML     30K 
42: R16         Note 9 - Basic and Diluted Earnings Per Common      HTML     50K 
                Share                                                            
48: R17         Note 10 - Activity of Business Segments             HTML     75K 
32: R18         Note 11 - Financial Information about Geographic    HTML     48K 
                Areas                                                            
14: R19         Note 12 - Related Party Transactions                HTML     23K 
36: R20         Note 13 - Leases                                    HTML     35K 
55: R21         Note 14 - Subsequent Events                         HTML     23K 
22: R22         Note 3 - Stock-based Compensation (Tables)          HTML     36K 
17: R23         Note 6 - Inventories (Tables)                       HTML     32K 
37: R24         Note 8 - Accrued Liabilities (Tables)               HTML     28K 
56: R25         Note 9 - Basic and Diluted Earnings Per Common      HTML     48K 
                Share (Tables)                                                   
23: R26         Note 10 - Activity of Business Segments (Tables)    HTML     75K 
18: R27         Note 11 - Financial Information about Geographic    HTML     45K 
                Areas (Tables)                                                   
35: R28         Note 13 - Leases (Tables)                           HTML     30K 
57: R29         Supplemental Disclosure of Non-cash Financing       HTML     24K 
                Activities (Details Textual)                                     
51: R30         Note 3 - Stock-based Compensation (Details          HTML     31K 
                Textual)                                                         
44: R31         Note 3 - Stock-based Compensation - Stock Option    HTML     45K 
                Activity (Details)                                               
13: R32         Note 4 - Investments (Details Textual)              HTML     29K 
29: R33         Note 5 - Recent Accounting Pronouncements (Details  HTML     26K 
                Textual)                                                         
50: R34         Note 6 - Inventories - Inventories (Details)        HTML     30K 
43: R35         Note 7 - Equity Investment in Unconsolidated        HTML     69K 
                Affiliate (Details Textual)                                      
12: R36         Note 8 - Accrued Liabilities - Accrued Liabilities  HTML     27K 
                (Details)                                                        
28: R37         Note 9 - Basic and Diluted Earnings Per Common      HTML     48K 
                Share - Reconciliation of Net Income and Number of               
                Shares Used in Computations of Basic and Diluted                 
                EPS (Details)                                                    
49: R38         Note 10 - Activity of Business Segments (Details    HTML     19K 
                Textual)                                                         
45: R39         Note 10 - Activity of Business Segments -           HTML     26K 
                Consolidated Net Sales (Details)                                 
59: R40         Note 10 - Activity of Business Segments -           HTML     36K 
                Reconciliation of Total Segment Income to Total                  
                Consolidated Net Income (Details)                                
39: R41         Note 10 - Activity of Business Segments -           HTML     26K 
                Consolidated Net Property and Equipment, Goodwill                
                and Intangible Assets (Details)                                  
21: R42         Note 11 - Financial Information about Geographic    HTML     37K 
                Areas - Consolidated Net Sales and Long-lived                    
                Asset Information by Geographic Area (Details)                   
27: R43         Note 12 - Related Party Transactions (Details       HTML     20K 
                Textual)                                                         
58: R44         Note 13 - Leases (Details Textual)                  HTML     31K 
38: R45         Note 13 - Leases - Future Minimum Lease Payment     HTML     37K 
                (Details)                                                        
40: XML         IDEA XML File -- Filing Summary                      XML    105K 
26: EXCEL       IDEA Workbook of Financial Reports                  XLSX     45K 
 6: EX-101.INS  XBRL Instance -- apt-20190930                        XML    880K 
 8: EX-101.CAL  XBRL Calculations -- apt-20190930_cal                XML    104K 
 9: EX-101.DEF  XBRL Definitions -- apt-20190930_def                 XML    632K 
10: EX-101.LAB  XBRL Labels -- apt-20190930_lab                      XML    484K 
11: EX-101.PRE  XBRL Presentations -- apt-20190930_pre               XML    672K 
 7: EX-101.SCH  XBRL Schema -- apt-20190930                          XSD    112K 
46: ZIP         XBRL Zipped Folder -- 0001437749-19-021693-xbrl      Zip     74K 


‘EX-101.DEF’   —   XBRL Definitions — apt-20190930_def


This Exhibit is an XBRL XML File.


                                                                                                                                                                                
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