Abstract: The invention refers to a dimming cap for a lamp with two separate radiation sources and, in particular, for a two-filament incandescent lamp, which has a concave shape with a base surface from which a circumferential side wall extends at least to a height H0 above the base surface, wherein the dimming cap, in a cross section formed at a height H0 parallel to the base surface, has a width (w0) that is constant within a tolerance of ±0.1 mm over a first longitudinal section of the dimming cap, and which decreases over a second longitudinal section extending from the first longitudinal section to a first end of the dimming cap, and the height of the sidewall corresponds within a tolerance of ±0.1 mm over the first longitudinal section to the constant height H0, wherein it increases over the second longitudinal section, wherein the first longitudinal section is between 70% and 98% of the length of the dimming cap in the cross-section formed at the height H0.