TRC Training and Certification L4 - Master RefurbisherTRC Level 4 Master Refurbisher Level 4 is the highest certification in the TRC framework. This level is not about how fast you can apply a skin. It is about judgement knowing whether a device should be refurbished at all, how it should be repaired, and where effort adds real commercial value. A Level 4 Master Refurbisher is trained to recover heavily damaged stock and turn it into Grade A devices using a controlled mix of repair, paint, skins, and