The PCR6060 is a Logic Level Thyristor which is commonly used with microcontrollers and other low voltage systems for switching applications. The Thyristor has an on-state current of 600mA with a reverse blocking voltage of 600V.
2P4M is a solid state semiconductor device called Thyristor or SCR (Silicon Controlled Rectifier). The device is designed to have highly sensitive trigger levels and is suitable for applications where available gate currents are limited.
2N1595 is a solid state semiconductor device called Thyristor or SCR (Silicon Controlled Rectifier). It is an industrial-type, low-current device available in a three-lead package ideal for printed-circuit applications.