There are two ways to dereference an array, depending on what you need to do. See perlref and perlreftut for the details.

In short, to dereference an entire array, use:

my @array = @{ $vendor_size_hash{$j} };
[download]

To dereference a single element in the array, use:

my $el = $vendor_size_hash{$j}[$number];
[download]