Spec's below.. for parameters in lamp filaments if useful in getting into reflector type etc. education and undertanding about the stacking and size of a filament, and the role in type of reflector also. This is SCIENCE!!!. Thanks in hoping to learn also. Filament Types: 2c-(x) / 2cc-(x) = (2cc-6 / 2cc-8) A Number Preceding the coil type indicates there are more than one filament in the lamp, on separate contacts. Note, Middle Pin is usually the common or neutral. c-(x)V / cc-(x)V = An arbitrary number sometimes followed by a letter to indicate the arrangement of the filament on the supports. c-2 = Dual vertical coiled filaments connected together by a straight no-coil filament at the top. c-2F = c-13 type “hung filament” between contacts and upper convex rack assy. for filament loop. c-2R / cc-2R = Small Filmt. Coil sym. to c-9 but without supports, Filament makes Convex curve between contacts, as opposed to cc-6 which is simply stretched between contacts. c-2V / cc-2V = Filmt. Coil w. Center Raised Support which raises center of filmt. higher than filmt. contacts/attachments. c-5 = Filmt Coil w. 5 supports including Filament Contacts. Filament shape is close together and balled up shape. c-6 / cc-6 = Filament Coil with Axis of Coil Perpendicular to Pins (Normal Side Supported)Filmt. c-7A = Filmt. Coil w. 7 supports from stem “M” shaped (?not including contact points) c-8 / cc-8 = Filament Coil with Axis of Coil Parallel to Pins (On End Vertical Top&Bottom Supported) c-8z = Filament coil with rigid supports and heavier filament. c-9 = Filmt. Coil with 4 supports making up a convex or arc shape out of the stem. c-11 / cc-11 = Filmt. Coil sym. to c-5, but smaller with 5 supports, making a “W” Shape. c-12 = c-6/c8 type Filament Coil stretched between two contact/supports of different length, making a filament from the side view smaller in length but three dimensionally longer and thus brighter from the side than a c-8 type filament c-13 / cc-13 = Filmt Coil Sym. to c-11/c-7a, “Lazy M Shaped” but larger and with coil not stretched between supports, but with coil hung/draped between two upper and one lower support. (?This arrangement is better for thicker high-wattage filaments, but has a longer time to incandess, and is less shock resistant while lit., it is also more likely to deform with time.) c-17A = Filament shape making latticework of supports, and decorative polyhedral shapes. cBar6 = Filament Coil Which is almost Flat From the Side, and Wide to the Top (On End Vertical Side Supported) FF is Bot. Supported. cc-13 MP = Mono Plane Filament Coil Grid single filament wide, with many rows of coiled coils next to each other. cc-13 BP = Bi-Plane Filament Coil Grid, Grid is double wide, sym. to Monoplane, but with rows double (even/odd) thick, and half as wide for the same amount of coil length. C = Coiled Wire Filament, this effectively shortens the width of the filament to allow a smaller focal center and smaller bulb. In Gas Filled filaments, reduced thermal losses and increases efficiency. The number following the coil identification letters denotes the arrangement of the filaments on the supports. A number before the letter denotes a double or triple filament. Wire wound into a Helical Coil, or is Deeply Fluted CC = Coiled Coil Wire Filament. Wire wound into a Helical Coil, This Coiled Wire is Wound Again into a Helical Coil. S = Straight Wire Filament, not coiled. S-2 = Straight Wire Filament sym to c-2R but w/o coil S-6 = Straight Wire Filament making S-curve between contact/support posts.