CorePRO Samplers provide more strength and a better sample! We got tired of hearing complaints about the flimsiness of other core samplers. CorePRO samplers provide much more strength and a better sample. This proprietary design uses three 5-ft long sections that screw together for portability. The bottom section has a built-in foot valve to hold the sample for blanket observation. Tubes have tape markings every foot without numbers (order optional self-stick waterproof numbers below). You can also purchase individual midsections for lengthening beyond 15-ft or for repair if you run over it with a truck. The famous 15-ft CorePRO Jr. is relatively flexible with a 1"OD. It has improved joints with stronger fittings and no rivets. Connect up to four sections for 20-ft maximum length. Samplers offer economy plus durability.