Spare firing valve spring part S07 for 1911 blowback model 4.5mm CO2 air pistols that use this style of magazine:

Replacement 1911 blowback CO2 air pistol magazine gas routing rubber.

Fits many models including
Umarex 1911 M45 A1 CQBP
Umarex 1911 Commander
Milbro 1911
Swiss Arms 1911
Remington 1911
Sig Sauer 1911 with complete drop out (we the people)
Barra 1911
Bruni US Combat 1911 CBB
Gamo Red Alert RD-1911