This is the mounting bracket for my 2.5 lb extinguishers in the Bronco. Held in place on roll bar w/ 2 hose clamps. Very tight and they haven't come loose when bouncing and bumping during last 5 years. Cheap too and no strap to release. Just yank and out they come. Ad below says for 5 lb. but mine are for 2.5 lb.
http://www.ebay.com/itm/FIRE-EXTINGUISHER-SPRING-CLIP-VEHICLE-BRACKET-5-/121270715795
http://www.ebay.com/itm/FIRE-EXTINGUISHER-SPRING-CLIP-VEHICLE-BRACKET-5-/121270715795