A lighting device includes a lighting unit with two arms formed on two ends thereof. The arms each include at least one reception portion. Multiple attachments each have a slide and a clip. The slide of each attachment is slidably engaged with the at least one reception portion of each arm. The clip is pivotably connected to the slide. Each clip includes a slot so as to clip a hat visor. The clip is adjustable by sliding the slide relative to the at least one reception portion. Also, the clip is pivotable relative to the slide to adjust a direction of the slot. The lighting device is able to clip to a hat visor of different shapes by sliding the slide relative to the at least one reception, and by pivoting the clip relative to the slide.