Use IMTUG for targeted training, one or two fingers at a time - even your thumb. Can't quite put away a No. 2 CoC? Hit your pinky and ring fingers with an IMTUG3 or IMTUG4 and see what happens. Want to certify on the No. 3 CoC or beyond? Meet IMTUG5, IMTUG6, and IMTUG7. Want a portable way to train your pinch grip? IMTUG1, IMTUG2, or IMTUG3 should be in your pocket. Designed to target your fingers one or two at a time. The perfect and portable way to train your thumb .Proprietary IronMind GR8 springs in 7 strengths: accurate, precise, durable. Soft-tissue friendly, ergonomically designed aluminum handles. CoC compatible: works hand-in-glove with Captains of Crush Grippers. Choose the IMTUG based on the relative strength of your fingers: Thumb - weakest - use an easier IMTUG. Ring and pinky fingers - moderate - use a medium IMTUG. Index and middle fingers - strongest - use a tougher IMTUG. Which IMTUG Should You Choose? Use the following guide to select the right level of IMTUGs based on which Captains of Crush Gripper you are training with. Guide or Sport - IMTUG1, IMTUG2. Trainer or No. 1 - IMTUG2, IMTUG3, IMTUG4. No. 1 or No. 2 - IMTUG3, IMTUG4, IMTUG5. No. 2 or No. 3 - IMTUG4, IMTUG5, IMTUG6. No. 3 or No. 4 - IMTUG6, IMTUG 7. IMTUG2: For those who are working with the Guide or Sport CoC Grippers; and who want to train their index/middle fingers.