Chapman has been making their screwdriver "kits" for a long time and I've been a user for over a decade. I'm always looking for products made in the USA to sell on my web pages so I decided to become a dealer. 

Each Chapman Tools kit has a precision twenty tooth ratchet made of stainless steel that has a short 18 degree working arc. Reverse action is obtained by simply turning the ratchet over (and reinserting the bit). The Screw Driver Handle is designed for comfortable, quick turning of fasteners while offering a precise feel for final tightening. A set screw in the barrel is used to lock in an adapter or the extension. The extension can be used alone with either the ratchet or screwdriver handle. Extensions can be stacked together for a longer reach. A set screw in the barrel is used to lock in the adapter bit or another extension. For some unknown reason Chapman calls their screwdriver bits, "adapters", but hey, they make them, they can call them whatever they want. The adaptors each have a ball detent that positively snaps the bit into the handle or extension. 

Kit 8900 is the Deluxe Gunsmithing Kit, containing the standard Allen Hex Type adapters, plus fourteen specialty Slotted Head adapters designed for gun repair work, in a hard pack case.
The 8900 Kit contains the following tools:

1 - Chapman Ratchet
1 - Extension
1 - Screw Driver Handle
10 - Allen Hex Adapters (Size indicates distance across flats):  

.050", 1/16", 5/64", 3/32", 7/64", 1/8", 9/64", 5/32", 3/16". 7/32"

12 - Slotted Head Adapters (Size indicates blade width x thickness):

0.125" x 0.023", 0.160" x 0.030", 0.190" x 0.025", 0.190" x 0.037", 0.230" x 0.037", 0.250" x 0.025", 0.250" x 0.037", 0.328" x 0.030", 0.328" x 0.037", 0.375" x 0.025", 0.375" x 0.037", 0.375" x 0.050"

2 - Phillips Head Adapters (Size indicates standard Phillips numbers): 

No. 1, No. 2

Kit 9600 is the Basic Gunsmithing Kit, containing fourteen specialty Slotted Head adapters designed for gun repair work, and one Allen Hex Type adapter for tightening set screws in the handle and extension. All packaged in a hard pack case.
Kit contains the following tools:

1 - Chapman Ratchet
1 - Extension
1 - Screw Driver Handle

14 - Slotted Head Adapters (Size indicates blade width x thickness):

0.125" x 0.023", 0.160" x 0.030", 0.190" x 0.025", 0.190" x 0.037", 0.230" x 0.037", 0.250" x 0.025", 0.250" x 0.037", 0.328" x 0.030", 0.328" x 0.037", 0.375" x 0.025", 0.375" x 0.037", 0.375" x 0.050"
Plus one each  extra  0.125" x 0.023" and  0.160" x 0.030" adapter.

1 - Allen Hex Adapter (Size indicates distance across flats):

.050"

2 - Phillips Head Adapters (Size indicates standard Phillips numbers):

No. 1, No. 2

Kit 1500 "G"broadens the 9600 Kit applications Allen Hex and Metric Hex adapters in a soft pack case..
Kit contains the following tools:

11 - Allen Hex Adapters (Size indicates distance across flats):

1 - Square Drive Adapter:

1/4" adapter for 1/4" drive sockets.

7 - Metric Adapters (Size indicates distance across flats):

1.5mm,  2.0mm, 2.5mm, 3.0mm, 4.0mm, 5.0mm, 6.0mm