This drop screwdriver, produced by Matt Brown, RPT, speeds up regulation of drop screws and repetition spring adjustment screws that have cylindrical, slotted 3/32" (2.4mm) diameter heads, such as those used in Renner parts.
The steel barrel (2.5mm inside diameter) at the end of the screwdriver fits over the screw head, preventing the screwdriver from slipping off the screw. There is no need to pre-align the blade with the slot: Once the screwdriver is over the screw, just turn the screwdriver until the blade engages with the slot, and proceed with the adjustment.