This type of brake clevis is commonly used to connect a power brake booster pushrod or extension rod to the brake pedal arm on many vehicles. The "3/8-24" refers to the thread size, where 3/8" is the thread diameter and "-24" indicates 24 threads per inch (fine thread). The "2.25''" dimension refers to the overall length of the clevis. 

2.25” Universal 3/8-24 Brake Clevis