We have two adapters that fit the Benjamin P-Rod pistol.
This adapter extends the shroud 1.5 inches so there's no need to remove the suppressor to fill the gun.
It pairs nicely with a .22/25 Tanto 1/2x20 UNF thread, bolt endcap which will make this pistol very quiet.
https://donnyfl.com/collections/ldc/products/1-22-x-5-inches-tanto?variant=11782988759083
This adapter does the same thing, but without the extra length.
Try it with a Tatsu #S31 for a great look and awesome silence.
https://donnyfl.com/collections/ldc/products/1-6-x-4-25-inches-tatsu?variant=33070871183403