A rain gutter system with a first elongated member and a second elongated member is disclosed. The first elongated member may include a first interior surface and a first exterior surface. The first interior surface may include an elongated retaining shoulder disposed along a first elongated member length. The second elongated member may include a second interior surface and a second exterior surface. The second exterior surface may include an elongated ridge disposed along a second elongated member length. The second elongated member may be configured to slide inside the first elongated member along the first elongated member length, and the elongated ridge may be configured to engage with the elongated retaining shoulder when the second elongated member slides inside the first elongated member.