Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
How many case deflectors are there for the Colt 646?

### Inputs:
table_name: table, columns: ['Colt model no.', 'Military designation', 'Barrel Length', 'Barrel', 'Handguard type', 'Buttstock type', 'Pistol grip type', 'Lower receiver type', 'Upper receiver type', 'Rear sight type', 'Front sight type', 'Muzzle device', 'Forward assist?', 'Case deflector?', 'Bayonet lug?', 'Trigger pack']

### Response:
SELECT COUNT Case deflector? FROM table WHERE Colt model no. = 646