Photochromic, bis-indenofused naphthopyrans with the general Formula: wherein the radicals R 1, R 2, R 3, R 4, R 5, R 6, R 7 and R 8, respectively independently of each other, represent a substituent selected from the group α consisting of a hydrogen atom, a (C 1 -C 6) alkyl radical, a (C 1 -C 6) thioalkyl radical, a (C 3 -C 7) cycloalkyl radical, which can have one or more heteratoms, a (C 1 -C 6) alkoxy radical, a hydroxy group, a trifluoromethyl group, bromine, chlorine, fluorine, an un-, mono- or disubstituted phenyl-, phenoxy-, benzyl-, benzyloxy-, naphthyl- or naphthoxy radical, the substituents in turn being able to be selected from the group α, preferably from (C 1 -C 6) alkyl, (C 1 -C 6) alkoxy, bromine, chlorine or fluorine; m und n, independently of each other, representing a whole number from 1 to 4, or the radicals R 1 and R 2, together with the carbon atom bonded to these radicals, form a 5- to 7-membered carbo- or heterocyclic ring, which possibly carries one or more substituents from the group α, but also one to three aromatic or heteroaromatic ring systems being able to be fused on this ring, the ring system(s), independently of each other, being selected from the group β, consisting of benzene, naphthalene, phenanthrene, pyridine, quinoline, furan, thiophene, pyrrol, benzofuran, benzothiophene, indole and carbazole, which in turn can be substituted with one or more substituents, selected from the group α, and if two of these substituents carried on the 5- to 7-membered carbo- or heterocyclic ring are situated on the same ring carbon atom, these in turn being able to form a 5- to 7-membered carbo- or heterocyclic ring, or the radicals R 5 and R 6, together with the carbon atom bonded to these radicals, form a 5- to 7-membered carbo- or heterocyclic ring, which possibly carries one or more substituents from the group α, but also one to three aromatic or heteroaromatic ring systems being able to be fused on this ring, the ring system(s), independently of each other, being selected from the group β, consisting of benzene, naphthalene, phenanthrene, pyridine, quinoline, furan, thiophene, pyrrol, benzofuran, benzothiophene, indole and carbazole, which in turn can be substituted with one or more substituents, selected from the group α, and if two of these substituents carried on the 5- to 7-membered carbo- or heterocyclic ring are situated on the same ring carbon atom, these in turn being able to form a 5- to 7-membered carbo- or heterocyclic ring, or two adjacent radicals R 3 form a fused benzene ring, which can be un-, mono- or disubstituted, the substituents in turn being able to be selected from the group α; or two adjacent radicals R 7 form a fused benzene ring, which can be un-, mono- or disubstituted, the substituents in turn being able to be selected from the group α; and B and B', independently of each other, are selected from the following groups a) or b), a) being mono-, di- and trisubstituted aryl radicals, the aryl radical being phenyl, naphthyl or phenanthryl; b) being unsubstituted, mono- and disubstituted heteroaryl radicals, the heteroaryl radical being pyridyl, furanyl, benzofuranyl, thienyl, benzothienyl, 1,2,3,4-tetrahydrocarbazolyl or julolidinyl, the substituents of the aryl- or heteroaryl radicals in a) and b) being those selected from the previously defined group α or from the group x, consisting of amino, mono-(C 1 -C 6) alkylamino, di-(C 1 -C 6) alkylamino, on the phenyl ring, un-, mono- or disubstituted mono- and diphenylamino, piperidinyl, N-substituted piperazinyl, pyrrolidinyl, imidazolidinyl, pyrazolidinyl, indolinyl, morpholinyl, 2,6-dimethylmorpholinyl, thiomorpholinyl, azacycloheptyl, azacyclooctyl, un-, mono- or disubstituted phenothiazinyl, un-, mono- or disubstituted phenoxazinyl, un-, mono- or disubstituted 1,2,3,4-tetrahydroquinolinyl, un-, mono- or disubstituted 2,3-dihydro-1,4-benzoxazinyl, un-, mono- or disubstituted 1,2,3,4-tetrahydroisoquinolinyl, un-, mono- or disubstituted phenazinyl, un, mono- or disubstituted carbazolyl, un-, mono- or disubstituted 1,2,3,4-tetrahydrocarbazolyl and un-, mono- or disubstituted 10,11-dihydrodibenzo[b,f]azepinyl, the substituent(s), independently of each other, in turn being able to be selected from (C 1 -C 6) alkyl, (C 1 -C 6) alkoxy, bromine, chlorine or fluorine; or two directly adjacent substituents of the aryl- or heteroaryl radicals in a) and b) representing a V-(CR 8 R 9) p -W grouping, p being = 1, 2 or 3, the radicals R 8 and R 9, respectively independently of each other, representing a substituent selected from the group α, and V and W, independently of each other, being able to be -O-,-S-, -N(C 1 -C 6) alkyl, -NC 6 H 5, -CH 2 -, -C(CH 3) 2 - or C(C 6 H 5) 2 -, two or more adjacent CR 8 R 9 units of this V-(CR 8 R 9) p -W grouping being able to be part of a benzene ring fused thereon, which respectively in turn can have one or more substituents selected from the group α, or V and/or W, together with the respectively adjacent CR 8 R 9 unit, representing a fused benzene ring, which can be un-, mono- or disubstituted, the substituents thereof being able to be selected from the group α. a) being mono-, di- and trisubstituted aryl radicals, the aryl radical being phenyl, naphthyl or phenanthryl; b) being unsubstituted, mono- and disubstituted heteroaryl radicals, the heteroaryl radical being pyridyl, furanyl, benzofuranyl, thienyl, benzothienyl, 1,2,3,4-tetrahydrocarbazolyl or julolidinyl,