Simpson 5-1/4X8 Face-Mount Hanger HGUS5.50/8 PACK:12 Pk and what material are they

and what material are they made from

this black powder-coat finished connector features a seat that provides an additional surface area of bearing extending beyond one side of the column

Does the bolt holder need to be removed after the concrete sets

The seat of the column cap provides additional surface area of bearing that extends beyond each side of the column

The Simpson Strong-Tie ECC74ROT End Column Cap is engineered to deliver strong

Simpson 5-1/4X8 Face-Mount Hanger HGUS5.50/8 PACK:12 Pk and what material are theySimpson Strong Tie HGUS5. 50 8 Face Mount Hanger is an extra heavy capacity face mount girder hanger engineered for demanding structural applications that require robust girder support. Featuring a value engineered design, this hanger delivers high load carrying performance at an economical price point, making it a trusted choice for heavy duty framing projects. Key Features Extra heavy capacity construction designed specifically for girder support