No1. Feature and Application 　　Two types can be chosen according to your special need. 　　(1) Springs with elastic locking are recommended if your application is e.g. back rest adjustment on train seats. Nitrogen is as the pneumatic medium. 　　(2) Springs with locking in the extension mode are recommended if you choose our products for height asjustment on balance tables. Gas and oil are as the medium. No2. Buying Guide 　　The picture only supplies the reference. 　　 If you want, please let us know the parameters . They're piston rod diameter, tube diameter, stroke, extended length and extension force. Our engineers will do their utmost to satisfy you. Ningbo Yulu Gas Spring Co.,Ltd is located in Ningbo city, Zhejiang province which enjoys convenient traffic and good geographic position. The company has been conducting our operations in strict accordance with ISO/TS16949 and ISO9001-2000 management system, optimize the allocation of enterprise resources, adopts manufacturing technology of Germany, The company staff make an excellent team with the design, management, marketing and so on. Our company has gas spring, lockable gas spring, damper, shock absorber and all kinds of gas spring connectors. They are widely applied in the fields such as machinery, furniture, automobile, textile machinery, aviation, motorcycles, medical equipment, the cabinets, the box, the bed, fitness equipment, the boat, the train , the tractor , the door and the window, massage chair and so on. We have a professional technical team responsible for designing and researching gas spring, have strength characteristic curve testing machine Fatigue tester, High cold temperature test box and CAD design system. We insist on satisfying customer's need for ourselves always, with the product of the superior quality, competitive price, humanizing of the after-sales service expand a market. Yulu Gas Spring Faith: quality and service come first. Each gas spring has to insure quality through strict examination, satisfied you with our products.