E821 Adjustable Fashionable Flashing Nylon LED Light Pet Dog Safety Collar,6 colors to choose LED pet collar;Material Black nylon webbing Flashing modes: slow,faster or keep on Battery: 2 batteries that can last up to 100 hours Size: Small: W-2.0cm X L-22 cm extends till 40 cm; Middle:W-2.0cm X L-32 cm extends till 50 cm;Large: W-2.0cm X L-48 cm extends till 60 cm