Ryobi Expand-It 18-Volt Lithium-Ion Cordless String Trimmer Power Head (Attachment Capable, Attachments, Battery and Charger NOT Included) - Walmart.com
RYOBI ONE+ 18V 13 in. Cordless Battery String Trimmer/Edger with 4.0 Ah Battery and Charger P2080 - The Home Depot