Automatic bobbins are now available to be purchased separately. As part of the maintenance schedule, bobbins should be replaced on a regular basis. Refer to your Owner’s Manual for maintenance schedule.Bobbins are a replacement part for the Halkey-Roberts type automatic inflators. Bobbins dissolve when immersed in water and cause the CO cylinder to inflate the PFD. All Mustang Survival automatic inflatable PFD’s come with cylinders and bobbins.*For recreational use, bobbins should be replaced every three years to avoid inadvertent inflation.Contains:One replacement bobbinRecommended for annual functional testing.Use only Mustang Survival re-arm kits. Use of other re-arm kits may result in improper operation or failure to operate and will void the product’s warranty.