A rotation angle indicating retainer assembly for use with and/or integrated with a hydraulically driven device for tightening and loosening a threaded fastener, the rotation angle indicating retainer assembly including: a retainer cap assembly having a substantially hollow cylindrical shape with an upper hollow portion, a lower hollow portion, a hollow disc, a ring having polygonal connection formations and a ball bearing assembly; a plunger assembly having substantially cylindrical shape with a connection portion, a depression portion, a compression spring and a lower retaining ring; a rotation angle scale assembly having a substantially hollow cylindrical shape with an upper hollow disc with an arrow indicator and a lower portion having polygonal formations; and a rotation angle indicator assembly having a substantially hollow cylindrical shape with an upper rotation angle dial, a lower portion having a rotation angle scale, an upper retaining ring, a wave spring and a friction ring, wherein when installed on the device: the plunger/button assembly is formed within the retainer cap assembly; the retainer cap assembly is: formed between the rotation angle indicator assembly and the rotation angle scale assembly; ttached nonrotatably relative to a square drive shaft torque output assembly of the device; the rotation angle indicator assembly is formed over the retainer cap assembly; the rotation angle scale assembly is: formed under the retainer cap assembly; and attached nonrotatably relative to a driving portion of a housing of the device. a retainer cap assembly having a substantially hollow cylindrical shape with an upper hollow portion, a lower hollow portion, a hollow disc, a ring having polygonal connection formations and a ball bearing assembly; a plunger assembly having substantially cylindrical shape with a connection portion, a depression portion, a compression spring and a lower retaining ring; a rotation angle scale assembly having a substantially hollow cylindrical shape with an upper hollow disc with an arrow indicator and a lower portion having polygonal formations; and a rotation angle indicator assembly having a substantially hollow cylindrical shape with an upper rotation angle dial, a lower portion having a rotation angle scale, an upper retaining ring, a wave spring and a friction ring, wherein when installed on the device: the plunger/button assembly is formed within the retainer cap assembly; the retainer cap assembly is: formed between the rotation angle indicator assembly and the rotation angle scale assembly; ttached nonrotatably relative to a square drive shaft torque output assembly of the device; the rotation angle indicator assembly is formed over the retainer cap assembly; the rotation angle scale assembly is: formed under the retainer cap assembly; and attached nonrotatably relative to a driving portion of a housing of the device. formed between the rotation angle indicator assembly and the rotation angle scale assembly; ttached nonrotatably relative to a square drive shaft torque output assembly of the device; the rotation angle indicator assembly is formed over the retainer cap assembly; the rotation angle scale assembly is: formed under the retainer cap assembly; and attached nonrotatably relative to a driving portion of a housing of the device. formed under the retainer cap assembly; and attached nonrotatably relative to a driving portion of a housing of the device.