Upgraded String Lights for Outdoor/Indoor: Super Bright - New upgraded LED bulbs. Safer - UL588 Approved plug in adapter. Extendable - 4 sets can be connected in series. Each one length is 105 feet, the max expandable length is 420 feet. Waterproof - Perfect for indoor/outdoor. 8 Lighting Modes - Romantic Decoration.Total length is 105ft, of which 99ft with lights. More Safer & Extendable & Widely Use: 29V low voltage plug with UL certified, make this lights safer than those without UL approval. Convinent to DIY the length, max 4 sets can be connected in series. Widely use to holiday season, bedroom decor, room decorations, wedding decorations, birthday decorations, holiday decorations, wall decor, home decor, teen room decor and so on.