Flimsy, deceptive warranty
"My first one lasted about 6 years, at which time the spring failed. Lymance replaced it through Northline per their ""Lifetime Warranty"". After about 6 years the second one failed."

New Lock-Top II 13" x 13" Chimney Cap/Damper - This premier energy-saving product is 90% more efficient than a traditional throat damper. With todays skyrocketing energy costs, the dollars saved in heat loss make a cap/damper combination a better choice than a chimney cap alone. The energy savings will quickly pay for the installation.
The Lock-Top II Chimney Cap/Damper arrives fully assembled and ready to install. The base mounts to a sweep's ring which then is connected to the flue tile with a high temp silicone sealant. A 30' stainless steel cable drops down the flue, and a hardware set mounts in the firebox. The end result is a damper that opens and closes with ease at the tug of a drop down cable. The Lock-Top II is equipped with a fire safety device that enables the damper to remain open in case of a chimney fire.
*Top-sealing dampers are not recommended with gas logs- failure to open could cause carbon monoxide to back up into the house.