10.0 - 12.0 cm. Eyes black. Bill very thin and fine, black. Crown black, but between August to March has a narrow white eyebrow. Nape, back, feathers that cover the wings, and rump blue-gray. Flight feathers of the wings brown, edged paler; inner feathers blackish with bold white edgings forming panel. Throat, chest, belly, flanks and feathers that cover undertail whitish; throat often contrastingly white. Uppertail black, with mostly white outer feathers (closed tail looks white below). Legs blackish. Males and females are different. Male: Crown black, but during August-March has a narrow white eyebrow. Female: Crown and eyebrow gray. Juveniles are similar to females.