Physical techniques Physical techniques involve extension devices, hanging weights, and vacuum pressure. There is also significant overlap between techniques intended to enlarge the penis and techniques intended to achieve other, related objectives, such as reversing impotence, extending the duration of erections, or enhancing sexual climax. Pumping Water-based vacuum pump Commonly called a "penis pump", a vacuum erection device, or VED, creates negative pressure that expands and thereby draws blood into the penis.[15][16] Medically approved VEDs, which treat erectile dysfunction, limit maximum pressure, whereas the pumps commonly bought by consumers seeking penis enlargement can reach dangerous pressure, damaging penis tissue.[17] To retain tumescence after breaking the device's airtight seal, one must constrict the penis' base, but constriction worn over 30 minutes can permanently damage the penis and cause erectile dysfunction.[18] Although vacuum therapy can treat erectile dysfunction sufficiently to prevent penis deterioration and shrinkage, [16] clinical trials have not found it effective for penis enlargement.[19][20] Jelqing The latinized name "jelqing" is the corrupt form derived from the Persian jalq zadan (جلق زدن), jalq meaning "to masturbate" followed by an auxiliary verb zadan meaning "to strike, hit or throb". Performed on the halfway tumescent penis, jelqing is a manual manipulation of simultaneous squeezing and stroking the shaft from base to corona. Also called "milking", the technique has ancient Arab origins. Despite many anecdotal reports of success, medical evidence is absent.[23] Journalists have dismissed the method as biologically implausible, [24] or even impossible, albeit unlikely to seriously damage the penis.[25] Still, if done excessively or harshly, jelqing could conceivably cause ruptures, scarring, disfigurement, and desensitization. Traction One type of traction device Traction is a nonsurgical method to lengthen the penis by employing devices that pull at the glans of the penis for extended periods of time. As of 2013, the majority of research investigating the use of penile traction focuses on treating the curvature and shrinkage of the penis as a result of Peyronie's disease, although some literature exists on the impact on men with short penises.[26] Scientific evidence supports some elongation by prolonged traction.