@ Regarding the presence or absence of

(*I am a beginner who has been studying programming for about a month.)
Thank you for looking at the question.
While studying a Ruby introductory book, I have some questions.
The Ruby version is ruby 2.6.5.

Here are the codes you may not know:

class Product
  attr_reader:name, :price

　default initialize (name, price)
    @name = name
    @price=price
  end

  def to_s
    "name:#{name}, price:#{price}"
  end
end

product=Product.new('A great movie', 1000)
product.to_s#=>"name:A great movie, price:1000"

The above code is in the chapter where inheritance is described.

I understand that the Product method overrides the to_s method.
However,
in the to_s method "name:#{name}, price:#{price}"
So why is the argument name, price?Isn't it @name, @price?

I looked into various things, but I didn't know.
Thank you for your cooperation.