Flux.Conv kernel definition

Consider the below command line, which defines kernel size as 5x5 and has seven output channels:

layer1 = Flux.Conv((5,5), 3 => 7, relu; bias = false)


  1. Which kernel(s), given that there are seven output channels, are effectively used on the above example? Are they pre-built?
  2. How do I specify my own (5,5) kernel? How do I specify my own set of seven (5,5) kernels?