Gearing on a handcycle: There are three chain rings located on the crank set or up near the handpedals. On the front wheel there is either 9 or 10 speed cassette. If there are 9, you will have 27 gears total and if there is a 10 speed cassette you will have 30 gears.
Technically though you cannot use all of the gears without crossing the chain, which can cause the chain to fall off, so there typically are about 20 usable gears.
The cassette numbers refer to the teeth, just like on the chain rings except that on the lower cassette, the smaller the number the harder the gear and vise versa.
Our Invacare® Top End® Force™ RX Handcycle has a 10-speed cassette with 11-36 as standard and the Invacare® Top End® Force™-3 Handcycle has a 9-speed cassette with 11-34 which is almost the same range. If you want to push more gear, which requires more strength because there are less climbing gears, there is an 11-28 cassette available with the upgrades packages on the Force RX Handcycle.
If you are just starting out, it is best to choose the standard options until you figure out your terrain and riding abilities.
Once you start riding it is important to learn how to change the gears to optimize your pedaling technique and maximize your speed.