Connecting Leads RED 500mm,4mm plugs both end-EIS-PH1055D offers a thoughtfully designed, durable resource for hands-on learning. 20" Length (500mm) 4mm (.15") insulated plug on both ends Great for physics classrooms and labs Use for any application requiring basic circuit assembly Red connecting lead. 500mm in length. 4mm insulated plug at both ends. Great for physics labs or any application requiring the assembly of basic circuits.