Patented Cylinders 2000 PLUS SeriesHere, we at Yale are proud to present the new range of 2000 PLUS series cylinders. 2000 PLUS Series 2000 PLUS Series 1500 PLUS SeriesHere, we at Yale are proud to present the new range of 1000 PLUS series cylinders. 1000 PLUS SeriesHere, we at Yale are proud to present the new range of 1000 PLUS series cylinders. 1000 PLUS Series 600 PLUS SeriesYale presents to you a range of 600 series PATENTED cylinders. 600 PLUS Series 600 PLUS Series 600 PLUS Series 500 PLUS SeriesYale presents to you a new range of 500 series cylinders.