This is an O-ring for the /5 model carburetors

The O-ring for the older model carburetors with a smaller diameter slide is a bit too tight for the later models with the larger diameter slide.

The O-ring for the /5 models (P/N 13111254932) is larger and therefor easier to fit.

Only use this O-ring on carburetors with 29.5 mm slides. For carburetors with 27 mm slides, use the smaller O-ring