A blade outer air seal, comprising: a plurality of arcuate segments (250; 250a, 250b), wherein a first arcuate segment (250; 250a) of the plurality of arcuate segments (250; 250a, 250b) comprises: an aft wall located at an aft end of the first arcuate segment (250; 250a); a first hook extending aft from the aft wall; and a first gusset, the aft wall comprising: a first radially extending protrusion, located at a first circumferential end of the aft wall; a second radially extending protrusion located at a second circumferential end of the aft wall opposite the first circumferential end; and a third radially extending protrusion disposed between the first radially extending protrusion and the second radially extending protrusion, wherein the first gusset extends from the first radially extending protrusion, characterised in that the aft wall comprises a plurality of third radially extending protrusions disposed between the first radially extending protrusion and the second radially extending protrusion, wherein a radial height of the first radially extending protrusion and the second radially extending protrusion as measured from a radially inward surface of the first arcuate segment (250; 250a) is greater than a radial height of the third radially extending protrusions as measured from the radially inward surface of the first arcuate segment (250; 250a), and wherein a radially outward surface of the first hook is radially inward of a midpoint of the aft wall, the midpoint of the aft wall being located halfway between the radially inward surface of the first arcuate segment (250; 250a) and a radially outward surface of the third radially extending protrusions. an aft wall located at an aft end of the first arcuate segment (250; 250a); a first hook extending aft from the aft wall; and a first gusset, the aft wall comprising: a first radially extending protrusion, located at a first circumferential end of the aft wall; a second radially extending protrusion located at a second circumferential end of the aft wall opposite the first circumferential end; and a third radially extending protrusion disposed between the first radially extending protrusion and the second radially extending protrusion, wherein the first gusset extends from the first radially extending protrusion, characterised in that the aft wall comprises a plurality of third radially extending protrusions disposed between the first radially extending protrusion and the second radially extending protrusion, wherein a radial height of the first radially extending protrusion and the second radially extending protrusion as measured from a radially inward surface of the first arcuate segment (250; 250a) is greater than a radial height of the third radially extending protrusions as measured from the radially inward surface of the first arcuate segment (250; 250a), and wherein a radially outward surface of the first hook is radially inward of a midpoint of the aft wall, the midpoint of the aft wall being located halfway between the radially inward surface of the first arcuate segment (250; 250a) and a radially outward surface of the third radially extending protrusions. a first radially extending protrusion, located at a first circumferential end of the aft wall; a second radially extending protrusion located at a second circumferential end of the aft wall opposite the first circumferential end; and a third radially extending protrusion disposed between the first radially extending protrusion and the second radially extending protrusion, wherein the first gusset extends from the first radially extending protrusion, characterised in that the aft wall comprises a plurality of third radially extending protrusions disposed between the first radially extending protrusion and the second radially extending protrusion, wherein a radial height of the first radially extending protrusion and the second radially extending protrusion as measured from a radially inward surface of the first arcuate segment (250; 250a) is greater than a radial height of the third radially extending protrusions as measured from the radially inward surface of the first arcuate segment (250; 250a), and wherein a radially outward surface of the first hook is radially inward of a midpoint of the aft wall, the midpoint of the aft wall being located halfway between the radially inward surface of the first arcuate segment (250; 250a) and a radially outward surface of the third radially extending protrusions.