A guy I know bought one of these as a calf sled. They make big models as well though. I think he liked it because they come with sides up to 18" high. They seem to have a nice hitch as well. Can be pulled with quad or snowmobile.
This is the biggest model I think.
Here is a smaller model with the hitch on it.
They are made by Otter Outdoors.
OTTER PRO X-LARGE SLED
The workhorse of the Otter Sled line!
Designed to haul wood, supplies, & gear, or whatever your job requires!
Outperforms all other brands.
Features:
Custom Compounded Polyethylene Construction
Raised Front For Ultimate Snow Resistance
Raised Rear For Cargo Security
Reinforced Outer Lip For Strength
Molded-In High Performance Ribs for extreme durability
Standard 5/16" Bottom
Granted a Seal of Approval by the North American Fishing Club
Dimensions:...93" L x 44" W x 18" H
Weight:..........75 LBS