These dust caps are made to fit the kiss DSV or any other standard 2nd stage hose and reg fitting.
they come as a set 1 male and 1 female (one for the hose and one for the reg)
The dust cap for the REG is fitted with a seal which makes these dust caps water proof so the regs can be removed and washed or stored with out the worry of getting water, dust or other things that might damage the valve inside.