Genuine AL-KO gaiter/ bellows . Al-Ko Part Number 2073890210 These bellows fit most Al-ko 30s, 60s 90s,120s/SR, 250s and 101VB couplings . With a 35mm draw tube. About 100mm long. 30mm round opening on the head end. 50mm opening on the other end. May fit other couplings.