The SY2S-02F1 is a hold-down spring accessory for IDEC DIN rail snap-mount relay sockets. It is specifically designed to secure single-pole relay and timer modules such as the RH1B, RAHB, and RBHB series onto socket models SH1B-05 and related DIN rail mounted bases. This spring provides mechanical retention and prevents accidental dislodging of relays during operation or vibration. The SY2S-02F1 is commonly used in industrial control panels, automation systems, and switchgear applications where reliable relay mounting is critical for system stability and safety.