Four precise apertures cut directly into existing windows define this monumental site-conditioned work by Robert Irwin, completed in 1997 and installed at the Museum of Contemporary Art San Diego. Measuring over nine feet tall and spanning more than twenty-six feet in width, the piece operates through subtraction rather than addition, reshaping the viewer's encounter with light, space, and perception by intervening in the architecture itself. The three apertures vary slightly in dimension, with the outer two measuring 24 by 30 inches and the center opening measuring 24 by 26 inches, calibrated differences that quietly complicate assumptions about symmetry and equivalence. What enters through those openings, whether coastal light, atmospheric shift, or the soft blur of an exterior environment, becomes the medium as much as the cuts themselves. This work belongs to a sustained practice in which Irwin treated phenomenological experience as the primary material. Rather than placing an object within a space, the artist altered the conditions of the space so that perception itself comes into focus. The title, a sequence of degree symbols, underscores this incremental logic, suggesting gradation, measurement, and the idea that experience accumulates in fine steps rather than dramatic gestures. Irwin's approach drew from his long engagement with the Californian light-and-space tradition while pushing well beyond it into a territory where architecture, atmosphere, and bodily awareness become inseparable. Works of this nature are rarely encountered outside institutional contexts, making this an exceptionally rare opportunity for a collector to acquire a piece that fundamentally redefines the space it inhabits.