Why does _links contain both a *self* and *product* link? Is this part of the HAL spec?

response.js

{  
   _embedded:{  
      products:[  
         {  
            id:1,
            name:"Starter Kit",
            description:"Starter Kit",
            msrp:5000,
            taxable:true,
            commissionable:true,
            status:"AVAILABLE",
            _links:{  
               self:{  
                  href:"http://localhost:8080/api/products/1"
               },
               product:{  
                  href:"http://localhost:8080/api/products/1"
               }
            }
         },
         {  
            id:3,
            name:"Starter Kit2",
            description:"Starter Kit",
            msrp:5000,
            taxable:true,
            commissionable:true,
            status:"UNAVAILABLE",
            _links:{  
               self:{  
                  href:"http://localhost:8080/api/products/3"
               },
               product:{  
                  href:"http://localhost:8080/api/products/3"
               }
            }
         },
         {  
            id:4,
            name:"Starter Kit234",
            description:"Starter Kit",
            msrp:5000,
            taxable:true,
            commissionable:true,
            status:"UNAVAILABLE",
            _links:{  
               self:{  
                  href:"http://localhost:8080/api/products/4"
               },
               product:{  
                  href:"http://localhost:8080/api/products/4"
               }
            }
         }
      ]
   },
   _links:{  
      self:{  
         href:"http://localhost:8080/api/products"
      },
      profile:{  
         href:"http://localhost:8080/api/profile/products"
      }
   },
   page:{  
      size:20,
      totalElements:3,
      totalPages:1,
      number:0
   }
}