rear button 50 of the shaft 48 has threads 60 similarly receiving the opposite end of the helical extension spring 52 in this manner the helical extension spring 52 is retained coaxially about the shaft 48 to occupy very little additional space it will be recognized however that other methods of biasing the shaft 48 including leaf springs and or the springs associated with electrical contacts of the third contact block 30 described below may also be used referring again to fig2 each of the contact blocks 26 and 28 and the spacer block 32 have opposed snap hooks 62 extending forward along axis 20 from upper and lower edges of their front faces these snap hooks 62 may be received by corresponding hook holds 64 formed in the abutting rear face of the housing 12 thus contact blocks 26 and 28 may be snapped to the rear face of the front housing 12 spacer block 32 includes corresponding hook holds 66 in its rear face that may receive the snap hooks 62 of the contact block 30 in this way contact block 30 may be snapped to spacer block 32 which may be snapped to the rear of housing 12 so that contact block 30 is spaced away from the housing 12 by the width of the spacer block 32 the snap hooks 62 are preferably molded as part of the housing of the contact blocks 26 28 and 30 and spacer block 32 to flex outward and then to engage the holds 66 to firmly retain the assembled parts together modular switches of.