New Bison Tumbler Colors! May 17, 2017 By Leave a Comment Introducing Orange & Purple Tumblers! You asked and we delivered! Orange and Purple Tumblers are available in both 20 oz and 30 oz sizes! Order today! Backyard Season Is Back Fire up the grill, dust off the patio set & enjoy backyard season. Get the Bison Coolers essentials you need to take summer to the next level. As a family-run business, we take pride in producing superior products with a warranty that’s second to none. We know you’ll love them as much as we do.