Untradeble item

Hi guys, im playing a private server. Some ppl can trade untradeble item, but i cant , noone cant. i learn it finally they're using a pak file.i tried to find wht's it and how its works but i didnt find it Can someone share it here pls. cuz i've got many anuhart gear and tahabatar's weap and somethin like that.Help me about this prob. I believe you can do it cheaterrrs

what server do u play? are u play in indo PS ? if u play in indo PS too i will give u this tricks ( exchange with anuhart elite set & tahabata spear)