A blade outer air seal (BOAS) assembly, comprising: a rotor blade configured to rotate about an axis (A-A'); a BOAS positioned radially outward from the rotor blade and having a forward-facing BOAS face; a shroud block positioned radially outward from the BOAS, having an aft-facing shroud face, and being configured to support the BOAS; a first bellows seal extending from the forward-facing BOAS face to the aft-facing shroud face and configured to reduce fluid leakage radially between the BOAS and the shroud block; and a second bellows seal, wherein: the shroud block includes a shroud main body, a shroud forward radial portion extending radially inward from the shroud main body, and a shroud forward axial portion extending axially aft from the shroud forward radial portion; the BOAS includes a BOAS main body, a BOAS forward radial portion extending radially outward from the BOAS main body, and a BOAS forward axial portion extending axially forward from the BOAS forward radial portion; the forward-facing BOAS face is defined by the BOAS forward radial portion; the aft-facing shroud face is defined by the shroud forward radial portion; the first bellows seal is located between the shroud forward radial portion and the BOAS forward radial portion; the BOAS further includes an aft-facing BOAS face; the shroud block further includes a forward-facing shroud face; and the second bellows seal extends from the aft-facing BOAS face to the forward-facing shroud face and is configured to further reduce the fluid leakage radially between the BOAS and the shroud block. a rotor blade configured to rotate about an axis (A-A'); a BOAS positioned radially outward from the rotor blade and having a forward-facing BOAS face; a shroud block positioned radially outward from the BOAS, having an aft-facing shroud face, and being configured to support the BOAS; a first bellows seal extending from the forward-facing BOAS face to the aft-facing shroud face and configured to reduce fluid leakage radially between the BOAS and the shroud block; and a second bellows seal, wherein: the shroud block includes a shroud main body, a shroud forward radial portion extending radially inward from the shroud main body, and a shroud forward axial portion extending axially aft from the shroud forward radial portion; the BOAS includes a BOAS main body, a BOAS forward radial portion extending radially outward from the BOAS main body, and a BOAS forward axial portion extending axially forward from the BOAS forward radial portion; the forward-facing BOAS face is defined by the BOAS forward radial portion; the aft-facing shroud face is defined by the shroud forward radial portion; the first bellows seal is located between the shroud forward radial portion and the BOAS forward radial portion; the BOAS further includes an aft-facing BOAS face; the shroud block further includes a forward-facing shroud face; and the second bellows seal extends from the aft-facing BOAS face to the forward-facing shroud face and is configured to further reduce the fluid leakage radially between the BOAS and the shroud block. the shroud block includes a shroud main body, a shroud forward radial portion extending radially inward from the shroud main body, and a shroud forward axial portion extending axially aft from the shroud forward radial portion; the BOAS includes a BOAS main body, a BOAS forward radial portion extending radially outward from the BOAS main body, and a BOAS forward axial portion extending axially forward from the BOAS forward radial portion; the forward-facing BOAS face is defined by the BOAS forward radial portion; the aft-facing shroud face is defined by the shroud forward radial portion; the first bellows seal is located between the shroud forward radial portion and the BOAS forward radial portion; the BOAS further includes an aft-facing BOAS face; the shroud block further includes a forward-facing shroud face; and the second bellows seal extends from the aft-facing BOAS face to the forward-facing shroud face and is configured to further reduce the fluid leakage radially between the BOAS and the shroud block.