HT57 50PF 15KVDC , HT57 10PF 15KVDC ceramic doorknob capacitors
Specifications

• Series: HT57 High Energy Doorknob Capacitor
• Working Voltage: 15 kVDC
• Max Power: 35 kVA
• Capacitance Options: 50 pF or 10 pF
• Dimensions: Approximately 1.187" diameter x 1.890" maximum length
• Application: Used in high-frequency, high-power equipment like radio transmitters, induction heating, and high-voltage power supplies. 

If you meant a specific limit sensor or hardware model that happens to use these capacitors in its circuit, could you provide the brand or equipment name so I can find the correct manual for you