WS2812B Mini 3535 RGB LED chip come out ,which Size is only 35*35, very small , ,and we have use those led chip to make led strip , which pcb width is less . 

Datasheet of WS2812B Mini 3535 rgb led chip is on the following , by the way , WS2812B 5050 rgb is compatible with SK6812 LED 5050 , can use same pcb , but 

WS2812B MINI can not use same PCB as SK6812 MINI

http://www.szledcolor.com//download/WS2812B%20Mini%203535.pdf