(1) if the ruling admits evidence, a party, on the record (A) timely objects or moves to strike; and (B) states the specific ground, unless it was apparent from the context; or (2) if the ruling excludes evidence, a party informs the court of its substance by an offer of proof, unless the substance was apparent from the context. The physical evidence is important because, unlike witness testimony, it doesnt lie and cant be accused of bias (such as racism). .