Poly.Sci.187, later retitled Mansbestfriend 4: Poly.Sci.187, is an instrumental studio album by American hip hop artist Sole.

Marisa Brown of AllMusic gave the album 2.5 stars out of 5, calling it "a dismal, electronic-leaning set that moves around sloshily without much heed for reason or direction.

"[2] She added, "The record's production is messy and distracted, never quite deciding what it actually wants to do, trying too much and too little at the same time, and since this is, for all practical consideration, an instrumental (Sole lays down and samples his own vocal tracks a few times, but the words are always low in the mix), this lack of attention to actual purpose detracts from it greatly.

"[2] Eric Harvey of Pitchfork gave the album a 7.0 out of 10, stating that it "proves that he can remove his signature musical element and still create a record that pushes many of the same affective buttons while moving out in unconventional directions.

"[3] Gentry Boeckel of PopMatters gave the album 2 stars out of 10, writing, "Poly.Sci.187 is easily the weakest recording in his catalogue, a tossed-off artistic diversion that hardly anyone besides his closest friends and labelmates will hear, or care about.