Anti Seize Technology AST-SEAL PH is the same as Loctite 545. This is for both Hydraulic and Pneumatic Close Fitting Thread Sealing Sealing and Securing Applications. It has a unique Purple Color. Anti Seize Technology AST-SEAL HYD is the same as Loctite 569. his is for only Hydraulic Close Fitting Thread Sealing Sealing and Securing Applications. It has a brown color.