1/2 inch x 3/32 inch. Includes: One bike chain and master link. For bikes with 5-8 rear cogs. Includes easy-install master link. To attach the ends together. Count your cogs to pick your chain. Look for the quicklink 350 or 450 chain tool from bell. Chain tool required. www.thebellgarage.com. For warranty details go to www.thebellgarage.com. Made in Taiwan.