They are a pair of MC4 connectors, 1 piece MC4 Male and 1 piece of MC4 Female.  MC4 Connectors are the industry standard for connecting photovoltaic panels for safe operation.  Dust free and water proof!

1) Housing: 100% GE PPO                                        

2) Degree of protection: IP68 (the highest protect level, dust proof and water proof that can withstand water immersion to a depth of 6.6 feet for 60 minutes.)                         

3) Contact resistance: 0.5mΩ

4) Contacts: Copper: Silver plated

5) Flame class: UL94-V0

6) Pin dimensions: Ø4mm                                      

7) Wire size range: 2.5~6.0mm²