PTS022 helps prevent scalding by physically restricting how far the temperature handle can turn past a safe limit.
Type: Temperature control stop sleeve / stop ring 
Function: Acts as an anti-scald safety device by limiting the range of the temperature handle. 
Compatibility: Used in many Lefroy Brooks ranges including the Godolphin GD 8700, BL 8736, MK 8822, DP 8706, and other compatible shower models. [2]
Location: Found inside the shower valve assembly, near the main thermostatic cartridge.