Grips are a crucial part of jiu jitsu; they are utilized constantly during a roll from gripping the gi to gripping your own wrists during a submission. Most academies will teach you how to break grips as this is also a crucial part of jiu jitsu. However, it is also important to strengthen your grip so that even the best grip-breaker will have a hard time getting you to let go. Grip exercises are very portable and can be performed nearly anywhere. 

1. Hand Grippers: This is a very common grip contraption you can buy nearly anywhere. Hand grippers exercise your ability to perform a crushing grip as you must close your grip against the resistance of the gripper. This small tool can be taken with you anywhere so you can get some grip exercise in no matter where you are.

2. Farmer's Carry: When you aren't at the gym with heavy weights accessible, you can use any other heavy item available to you. For example, if you have a gallon of water with a strap or a 5-gallon jug with handle, this can easily replace an official free weight. For added challenge, loop your belt on the strap and carry it by the belt. This will also strengthen your forearm muscles as well as your grip. 

3. JitsGrip Training Kit: If you want to invest in a jiu jitsu focused grip trainer, the JitsGrip Training Kit provides you with the essentials for all your grip exercise needs. It features grips made of gi material so your grips and knuckles will experience the same texture needed during your bjj rolls.