Genuine Sherwood 21533 Half Cam Plastic Sherwood replacement 18000 and G2900 series half cam liner for various Sherwood pumps. 2 cams required for 1 pump. Suitable for pumps G1804, G1806, G18061-01, G1808, G18081-01, G18082-01, G18082X, G1815-01, G1815X,...