External magazine Fits with Umarex HDP50 gen1 and GEN 2Accesorry for HDP 50  - 5 balls storage speedloader  
It is mounted directly on the rail without other screws. 
Fits very well in adjustable heel (find on aliexpress)
After you finish firing what you have in the pistol,
you block the supply spring, you turn the pistol and 
the 5 balls from the additional magazine will fall into the main magazine

Please think carefully before paying for the product 
because we cannot cancel an order because that means big losses for us 
because every sale (even the canceled ones) is commissioned by ebay 
as if it had been sold plus the promotion plus other commissions,
which we would lose them if a payment is cancelled