My damson plum tree (the small German baking plums) gave 40kg of plums this year. After pitting most of them with a knife or by smashing, I bought the Westmark plum stoner. It arrived quickly, from Germany to California, and it made the remainder of my pitting very easy. It is a great design, and safe to use. Note that this pitter works only for smaller plums, such as damson and California prune/Italian plums, but won't work for larger plums. (My plums are about 1"/2.5cm in diameter.)