This is a model by Otobiko Fujita of PJ AX. Inner diameter: 17.53, Throat diameter: 4.20 There are insertion marks from before purchase, but it is in very clean condition. I purchased it for my collection, but I will sell it. (Price at purchase: ¥28,500) *Regarding the shank, Holton and Paxman are not compatible. Alexander, Yamaha, and Schmidt are OK. Please refrain from extreme price negotiations. Thank you very much.