Police are linking two break-ins which netted high-value outdoor clothing worth around £25,000.
The first raid happened at an industrial unit in Lancaster on November 18, with thieves getting away with a large quantity of jackets and boots worth more than £10,000.
Five days later an a unit in Barnacre near Garstang was forcibly entered and a haul of hunting jackets, camping jackets and trousers worth close to £15,000 was stolen.
Both raids happened at around 7pm in the evening and detectives believe they are connected.
Officers are appealing for any information on either theft.
PC Matthew Betts of Lancaster Police said: “These crimes were similar in nature and we would appeal to anyone with information to contact us.
“Some of the clothing removed is not available anywhere else in this country and I would ask anyone who has been offered or bought this products to contact us immediately.”
The first break-in was in Wyresdale Road, Lancaster where the offenders gained access to the building by removing a window and cutting through metal bars.
In the second, at the Creamery Industrial Estate in Barnacre, the raiders also removed a window at the rear of the premises to get in.
It is believed the Barnacre company is the UK’s only supplier of some of the clothing taken, including items by Swazi, Norrona and Woolpower.
Anyone with information can contact police on 101 quoting crime reference number WB1509595 for the Garstang thefts or WB1509463 for the Lancaster incident.