(Fly Armor) Fly Armor attaches to horse gear to repel flies, gnats and mosquitoes. Each Fly Armor Cheek Band holds a replaceable Citronella oil insert (included) for up to four weeks of protection. Replace the inserts when they lose their effectiveness. Hook-and-loop attachments at each end allow you to fasten to your bridle, halter or reins. Vaporguard backing provides a barrier between noseband and your horse. Pair. 1.5" x 7". Two inserts.