K56 or K52

[Tartegogo]

So I am really enjoying receiving line pictures of masseurs from a place called spa285 but I can’t quite get one part of the message I am getting: 
 

ลูกศร (ชายแท้)รุก K56 ไลน์ 285.spa โทร 0970905133

it is clear except for K56

Sometime the boy’s name and description is followed by K52 or K54 instead of K56 
is that a penis size? It does seem to correlate to girth, but I can’t be sure. Or is it something else?

[vinapu]

condom size suitable for guy in question