Short answer. Three categories of personal property: property that is the subject of the offense; property that was stolen or embezzled, or is otherwise the proceeds or fruits of the offense; and property used or intended to be used as the means of committing an offense.
What the law says
A search warrant may be issued for the search and seizure of personal property: (a) Subject of the offense; (b) Stolen or embezzled and other proceeds, or fruits of the offense; or (c) Used or intended to be used as the means of committing an offense.
Rule 126, Section 3 — Personal property to be seized. Read the full provision →
Property that is the subject of the offense
The first category covers personal property that is itself the subject of the offense — property whose possession, transfer, or existence is what the crime is actually about. Prohibited items a person is charged with illegally possessing are the clearest example of this category, since the item itself is what makes the possession unlawful in the first place, rather than merely serving as evidence of some separate wrongdoing.
Stolen property and the proceeds or fruits of a crime
The second category reaches property that is stolen or embezzled and other proceeds, or fruits of the offense. This covers not only the item originally taken, but also what the offense actually generated or yielded — property connected to the crime through its origin as the gain from committing it, rather than through direct involvement in the act itself. Money or goods traceable to the crime's proceeds can fall within this category even where the original stolen item has since changed form.
Property used as the means of committing the offense
The third category is property used or intended to be used as the means of committing an offense — the instruments or tools involved in carrying out the crime, or property that was going to be used that way even if the offense had not yet been completed. This covers equipment or items that played, or were meant to play, an active role in the commission of the crime, distinguishing them from property that is merely incidental to it.
Why the categories are limited this way
A search warrant is not a general license to seize whatever officers find of interest. Limiting seizure to these three categories keeps the search tied to the specific offense the warrant was issued for, rather than becoming an open-ended search of a person's belongings — property outside these three descriptions is not what the warrant authorizes officers to take, whatever else they happen to encounter during the search and however incriminating it might otherwise look.