IF and that is big IF. If it is pre-strung by YY, they are usually BG43 at lower end of the tension. Note, they do not have the mark Yonex BG43. Usually they come unstrung and shop string them base on the customer request. However, shop can request to have it prestrung with $10 USD surcharge...
Thanks silentheart. You are correct that the string is not mark. Hence the question. Kids in school like it and it is very durable. However, kids are rough and I need to get rackets re-strung quite offen. Just looking to see what I tell the shop when I get them restrung the rackets and see anything cheaper then BG65 at $18.