On a Land Rover, the caliper design is very similar to those and there is a sleeve inside the bridge seal so it keeps it seated when you release the brake pedal and prevent it to suck air in the joint and un-bleed the system as you drive. This sleeve is nothing special, a piece of pipe with the correct length and diameter is all it needs. I used to drive a car with a caliper set that had been rebuilt without the sleeve and I have never been able to prevent them to pickup air...
On a Land Rover, the caliper design is very similar to those and there is a sleeve inside the bridge seal so it keeps it seated when you release the brake pedal and prevent it to suck air in the joint and un-bleed the system as you drive. This sleeve is nothing special, a piece of pipe with the correct length and diameter is all it needs. I used to drive a car with a caliper set that had been rebuilt without the sleeve and I have never been able to prevent them to pickup air...