The pup joint are used to adjust the height of full length tubing or casing strings, they are also used to asjust the depth of downhole tools.
Specifications:
Standard: API 5CT
Size: 1.9 inch to 18 5/8 inch
Grade: J55/K55/N80/L80/P110
Length: 2FT/3FT/4FT/5FT/6FT/8FT/10FT/12FT