Sharp edged t-posts can injure horses and livestock. Gallagher's Heavy Duty T-Post Topper Insulator can give you peace of mind as they protect animals from sharp edges.. Safe and flexible - add a single electric wire/tape/braid to the top of existing steel posts using this protective cap or attach wire/braid to the top. This top accommodates 3/8" wire. The front accommodates 1 1/2" tape and 3/8" wire. The T-Post Topper Insulator is designed to fit over the top of a T Post or Y-Post and can securely hold electric wire, tape or braid. It is made from UV resistant plastic for long life and strength and comes backed by a full 10-year manufacturer's warranty.