Type: 1. DL-25: suitable for tube size less than and equel to 6.50-20; 2. LLN-1120: suitable for tube size from 7.510-16 to 9.00-20; 3. LLN-1430: suitable for tube size from 10.00-20 to 12.00-20; 4. LLN-400: suitable for tube size 9.00-20 to 12.00-20.